Resistive memory

ABSTRACT

A memory device includes an upper conductive layer, a lower conductive layer, and a resistive, optical or magnetic matrix positioned between the upper and lower conductive layers.

This application is a continuation application from application Ser. No.13/300,571 claiming priority to application Ser. No. 12/905,069 claimingpriority to application Ser. No. 12/617,198, which claims priority toapplication Ser. No. 12/348,904, which in turn claims priority toapplication Ser. No. 11/867,566, which is a divisional of Ser. No.11/064,364, which claims priority to Provisional Application 60/560,053filed Apr. 6, 2004, the content of which is incorporated by reference.

BACKGROUND

The present invention relates to memory devices.

The success of the PC, networking, and communications-product marketshas been driven largely by Moore's Law, which says that IC densitydoubles every 18 months. Experts predict that CMOS scaling will continueto follow Moore's Law for at least another decade, but potentialbottlenecks could derail market success if not solved by new design ordevice technology. One of these bottlenecks is integrating precisionanalog and wideband RF circuitry in standard digital CMOS.

Applying Moore's Law to mixed-signal (analog and digital) chips is asignificant challenge. Higher transistor density and lower silicon costallow more complex digital circuitry, but most wireless or wirelinecommunications products require integrating RF, analog, and memory withthe digital logic. Advancements in submicron CMOS processing greatlybenefit digital logic and memory, but result in poor analog and RFperformance. Transistor matching, noise, resistors, capacitors, andinductors drive the density of analog circuits, and these parameters donot necessarily benefit from transistor scaling.

To compound the problem, digital-circuit design continues to benefitfrom advances in logic synthesis, accelerating the time-to-market ofdigital products. Analog circuit design has not historically benefitedsignificantly from CAD-tool advances, and remains a hand-crafted art.Consequently, analog circuits will be a limiting factor for mixed-signalSoC, both in terms of the increasingly larger percentage of the diethese circuits occupy, and in terms of their design time.

SUMMARY

Systems and methods are disclosed to form a memory device.

In one aspect, a memory device includes an upper conductive layer, alower conductive layer, and a resistive, optical or magnetic matrixpositioned between the upper and lower conductive layers.

In another aspect, a memory device includes an upper conductive layer, alower conductive layer, and a memory resistive (memristive) matrixpositioned between the upper and lower conductive layers.

In another aspect, a memory device memory device includes a first arrayof memory structures disposed in rows and columns and constructed over asubstrate, each memory structure having a first signal electrode, asecond signal electrode, and a resistive layer positioned between thefirst signal electrode and the second signal electrode.

In another aspect, a memory device includes a substrate; a first layerfabricated using semiconductor fabrication techniques; a second layerformed above the first layer, the second layer having one or moreresistive-bonding areas and one or more resistive memory elementsself-assembled to the second layer resistive bonding areas; and a thirdlayer formed above the second layer, the third layer having one or moreresistive-bonding areas and one or more resistive memory elementsself-assembled to the third layer resistive bonding areas.

In yet another aspect, a memory device includes an array of memorystructures disposed in rows and columns and constructed over asubstrate, each memory structure comprising a first signal electrode, asecond signal electrode, and a resistive layer coupled to the firstsignal electrode and the second signal electrode; a plurality of wordlines connected to the first signal electrodes of a row of memory cells;and a plurality of bit lines connected to the second signal electrodesof a column of memory cells.

Advantages may include one or more of the following. The system iscompact, power efficient, and dense. The molecular electronics in theabove system extend the miniaturization that has driven the density andspeed advantages of the integrated circuit in accordance with Moore'sLaw.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a programmable analog nano-array inaccordance with the present invention.

FIG. 2 is a schematic diagram of a first embodiment of a programmablenano-cell in accordance with the present invention.

FIG. 3 is a schematic diagram of a second embodiment of a programmablenano-cell in accordance with the present invention.

FIG. 4 is a block diagram of a wireless communication device comprisingnano antenna in accordance with the present invention.

FIG. 5 is a schematic diagram of the architecture of memory devicescomprising nano elements in accordance with the present invention.

FIGS. 6A-6B show perspective views of an exemplary single moleculemagnet data storage device, in this case a disk drive in accordance withthe present invention.

FIG. 7 is a diagram of a system having an array of nano-based chemicaland biological sensors in accordance with the present invention.

FIG. 8 is an exemplary diagram of an array of nano-based image sensorsin accordance with the present invention.

FIG. 9 depicts a cross-sectional view of a flexible photovoltaic cell.

FIG. 10 shows an exemplary power generation system.

DESCRIPTION Programmable Analog Nano-Array and Nano-Cells

FIG. 1 is a block diagram of a programmable array using nano-analogelectronics in an integrated circuit configuration. Nano-analog array 10includes a plurality of programmable analog cells 12 arranged along aplurality of interconnect channels that form a switching network whichincludes bus lines 13 and 14 for routing analog signals. Input andoutput signals are transferred between analog cells 12 and buses 13 and14 by means of analog switching devices such as transmission gatesthrough which analog signals can be transferred with little or nodistortion. Control over the switching devices is provided by digitalsignals that may be stored in a memory such as random access memory(RAM) or read-only memory included in the cell. Alternatively, acentralized memory array can be used to control the switching devices inall of the analog cells 12. As a further alternative, external memorycan be used if provision is made for routing the binary control signalsto individual analog cells 12. As yet a further alternative, controlover the switching devices may be directly provided by other digitalcircuitry instead of a memory array. Signal routing between bus 13 andbus 14 is provided by switching devices 19.

FIG. 2 is a schematic diagram of a programmable analog cell 12 includingan active circuit 22, switches 23-32, programmable nano-elements 33-39,and a static random access memory (SRAM) 40. Input signals are receivedon input terminals 15 and 16 and output signals are produced on outputterminals 17 and 18. Output terminals 17 and 18 are shown as connectedtogether to drive horizontal and vertical conductors 13 and 14. In analternative embodiment, output terminals 17 and 18 could be isolatedsuch that active circuit 22 drives output terminal 17 and another activecircuit included in programmable analog cell 12 drives output terminal18.

Fabrication of Nano Electronic Components and Systems

As described below, the nano-elements can be formed last in thefabrication sequence in one embodiment. Conventional semiconductorstructures are formed as is conventional, which for example includessemiconductor devices produced by photolithography or E-beamlithography. During the next to the last conventional step, goldelectrodes are formed. Then a resist layer is formed over the lastlayer, and selective etching is performed to expose the gold electrodes.A solution containing the nano-elements are spin-coated on top, wherethe nano-elements self-assemble to form one or more devices such asresistors, capacitors, inductors, antennas, emitters and sensors, amongothers. Other coating techniques compatible with the present inventioninclude hopper coating, curtain coating. The nano-elements bond topreselected spots on the gold electrodes and self-assemble to form aregular array of resistors, capacitors, inductors, acoustic emitters,acoustic sensors, light emitters, light sensors, among others. In oneembodiment, the nano-elements do not need patterning. In anotherembodiment, patterning of the nano-elements is accomplished by any ofthe generally available photolithographic techniques utilized insemiconductor processing. However, depending on the particular materialchosen, other techniques such as laser ablation or inkjet deposition orelectrostatic deposition may also be utilized to pattern thenano-elements. In particular nanoimprint lithography can be used topattern the nano-elements.

In another embodiment, the substrate may be formed from silicon, galliumarsenide, indium phosphide, and silicon carbide to name a few. Activedevices will be formed utilizing conventional semiconductor processingequipment. Other substrate materials can also be utilized, depending onthe particular application in which the array will be used. For examplevarious glasses, aluminum oxide and other inorganic dielectrics can beutilized. In addition, metals such as aluminum and tantalum thatelectrochemically form oxides, such as anodized aluminum or tantalum,can be utilized. Those applications utilizing non-semiconductorsubstrates, active devices can also be formed on these materialsutilizing techniques such as amorphous silicon or polysilicon thin filmtransistor (TFT) processes or processes used to produce organic orpolymer based active devices. Accordingly, the present system is notintended to be limited to those devices fabricated in siliconsemiconductor materials, but will include those devices fabricated inone or more of the available semiconductor materials and technologiesknown in the art.

The process of creating the first layer of electrical conductors mayconsist of sputter deposition, electron beam evaporation, thermalevaporation, or chemical vapor deposition of either metals or alloys andwill depend on the particular material chosen for the electricalconductors. Conductive materials such as polyaniline, polypyrrole,pentacene, thiophene compounds, or conductive inks, may utilize any ofthe techniques used to create thin organic films. For example, screenprinting, spin coating, dip coating, spray coating, ink jet depositionand in some cases, as with PEDOT, thermal evaporation are techniquesthat may be used.

Depending on the particular memory device being fabricated, theelectrical contacts may be created either on a substrate or directly onthe semiconducting polymer film. Patterning of the electrical conductorsis accomplished by any of the generally available photolithographictechniques utilized in semiconductor processing. However, depending onthe particular material chosen, other techniques such as laser ablationor inkjet deposition may also be utilized. In particular one my utilizednanoimprint lithography or techniques for forming nanowires. Foradditional information on nanoimprint lithography see for example, U.S.Application No. 20030230746, the content of which is incorporated byreference. Combinations of different conductive materials may also beutilized that might result in very different processes being utilized.For example it may be desirable to utilize PEDOT as the material for thelower electrical traces and indium tin oxide for the upper electricaltraces if erasure via light is desired. Another embodiment may use atypical metal such as tantalum, tungsten, or even highly dopedpolysilicon for electrical conductors deposited on the substrate and anorganic conductor such as PEDOT for electrical conductors deposited onthe semiconducting polymer film. The process of creating a third layerof electrical conductors on a second semiconducting polymer film, forthe applications utilizing such a layer, can be the same or similar tothat used for the first layer, depending on whether the electricalconductor is the same as that used for the first layer electricalconductors. The process of creating a semiconducting polymer film willdepend on the particular binder and organic dopant chosen. Theparticular binder and organic dopant chosen will depend, for example, onthe particular electronic properties desired, the environment in whichthe device will be used, and whether a thin dielectric film will beutilized. Depending on the particular binder chosen the appropriatesolvents are utilized that provide sufficient solubility for both thebinder and the organic dopant as well as providing appropriate viscosityfor the particular coating or casting process chosen. An exemplaryprocess for creating a semiconducting polymer layer uses HPLC gradetetrahydrofuran as a solvent to dissolve the binderbisphenol-A-polycarbonate and a mono-substituted diphenylhydrazonecompound (DPH) in appropriate concentrations to obtain the desiredelectrical properties. If a substrate is utilized, the composition andproperties of the substrate are also taken into consideration, in orderto obtain good adhesion between the substrate and the semiconductorpolymer layer, as well as the electrical conductors and thesemiconductor polymer layer. Adhesion promoters or surface modificationmay also be utilized. In addition, a planarizing layer may also beutilized, for example, when electrical conductors are formed on ratherthan in the substrate. The process of creating a multilayersemiconductor polymer film, for those applications utilizing such astructure, can be the same or similar as the process used to create thefirst layer, depending on whether the binder or organic dopant is thesame as that used for the first layer. The process of forming adielectric thin film, will depend on the particular material chosen, andmay consist of, for example, sputter deposition, chemical vapordeposition, spin coating, or electrochemical oxidation. For example,tantalum electrical conductors may be deposited using conventionalsputtering or electron beam deposition techniques. After the tantalum isdeposited a thin tantalum oxide layer may be formed electrochemically.This process may be performed prior to or after photolithographicprocessing to define the electrical conductors. Another embodiment mayutilize a thin silicon oxide layer deposited on the electricalconductors or on the semiconducting polymer film depending on whichelectrical conductor is chosen to have the thin dielectric film. A thinsilicon oxide film may be deposited by any of a wide range oftechniques, such as sputter deposition, chemical vapor deposition, orspin coating of a spin on glass material, to name a few. Still anotherembodiment may utilize a thin non-conducting polymer layer, such as thebinder polymer, deposited on the appropriate electrical conductors.Other embodiments may utilize self assembled monolayers or silanecoupling agents to produce a thin dielectric film. The process ofcreating a second or multilayer dielectric thin film, for thoseapplications utilizing such a structure, can be the same or similar asthe process used to create the first layer, depending on whether thethin dielectric film is the same as that used for the first layer. Theprocess of creating the second layer of electrical conductors willdepend, for example, on the particular binder and organic materialschosen as well as the presence or absence of the thin dielectric filmand its chemical composition. For example, a polyimide binder willtypically sustain higher temperatures than a polyethylene binder will.Thus, thermal or electron beam deposition of tungsten or platinumelectrical conductors may be used on a polyimide binder whereas chemicalvapor deposition, spin coating or thermal evaporation of an organicconductor may be desirable for a polyethylene binder. The particulardeposition process utilized will also depend on the degree of defectsgenerated in either the thin dielectric film if used or thesemiconducting polymer film. In addition, the particular process as wellas the process parameters will also be chosen to optimize adhesionbetween the film or films to which the electrical conductor material isdeposited on. The process of creating a fourth layer of electricalconductors, for those applications utilizing such a structure, can bethe same or similar as the processes used to create the first throughthird layers, depending on whether the fourth layer is the same as thatused for the first layer. A passivation layer can be used to protect thesemiconducting polymer film from damage and environmental degradationwhen appropriate. For example, a passivation layer providing a barrierto oxygen permeation can be desirable when utilizing a memory devicehaving an acceptor organic dopant or functional group because oxygen isa potential electron trap. In addition, depending on the particularorganic dopant and electrical conductors utilized it may also bedesirable to utilize a passivation layer providing a moisture barrier toreduce corrosion. Further depending on whether active devices arepresent an electrostatically dissipating or shielding film may also bedesirable.

Due to the nano-structure, the absolute capacitance values ofprogrammable nano-elements 33-39 are well controlled using self-assemblyprocesses. Additional degree of matching accuracy can be attained ifprogrammable elements 33-39 are carefully laid out on the die. Suchmatching accuracy results in a given binary control chemical structureproducing substantially equal capacitances when applied to each of theprogrammable elements 33-39. For this reason, operations of activecircuit 22 can be controlled using ratios of programmable resistance,capacitance, or inductance whenever possible. For example, in oneembodiment where the nano-elements 33-39 are capacitors, if it isdesired to operate amplifier 22 with a closed loop gain of 35/32, abinary control chemical structure “35” is applied to controlprogrammable capacitor 39 and a binary control chemical structure “32”is applied to control programmable capacitor 33. The resultingcapacitance ratio is 35/32.

Active circuit 22 is shown as an amplifier having inverting andnon-inverting inputs and an output. Analog cell 12 can also includecomparators and other types of active circuits, and can include morethan one active circuits of the same type. For example, a single cellcan incorporate several amplifiers controlled by programmablenano-elements 33-39 that act as capacitors to operate as an activefilter. Active circuit 22 typically includes an output buffer stage (notshown) for driving the capacitances and the load capacitances ofterminals 17 and 18.

SRAM 40 comprises memory storage for controlling the operation ofswitches 23-32 and switches included in programmable capacitors 33-39.To simplify the figure, such control is indicated by the dotted linefrom SRAM 40 to switches 23-26 and programmable capacitors 33-36.Switches 23-26 and programmable capacitors 33-36 can alternatively becontrolled by other types of memory, such as read only memory, or withcombinational logic.

It should be noted that programmable analog cell 12 can alternatively beimplemented with programmable nano-elements that include passiveelements other than switchable capacitors, such as programmablenano-resistors or programmable nano-inductors.

Dynamically Reconfigurable Logic-Analog Devices

In one embodiment, a field programmable array includes a matrix ofconfigurable logic and/or analog blocks embedded in a programmablerouting mesh. Each configurable logic/analog block (CLAB) can provideone or more of the functions provided by an AND gate, flip-flop, latch,inverter, NOR gate, exclusive OR gate, resistor, capacitor, inductor,LED, light sensor, as well as combinations of these functions to formmore complex functions. The particular function performed by the CLAB isdetermined by control signals that are applied to the CLAB from acontrol logic circuit. The control logic circuit is formed integrallywith, and as part of, the integrated circuit on which the CLAB isformed. If desired, control information can be stored and/or generatedoutside of this integrated circuit and transmitted to the CLAB. Theactual set of control bits provided to each CLAB on the integratedcircuit depends upon the functions that the CLAB and, more globally, theintegrated circuit are to perform. Each CLAB typically has a pluralityof input and output pins, and a set of programmable interconnect points(PIPs) for each input and output pin. The general interconnect structureof the field programmable array includes a plurality of interconnectsegments and a plurality of PIPs, wherein each interconnect segment isconnected to one or more other interconnect segments by programming anassociated PIP. A field programmable array also includes an access PIPthat either connects an interconnect segment to an input pin or anoutput pin of the CLAB. Because the PIPs are programmable, any givenoutput pin of a CLAB is connectable to any given input pin of any otherdesired CLB. Thus, a specific field programmable array configurationhaving a desired function is created by selected generation of controlsignals to configure the specific function of each CLAB, together withselected generation of control signals to configure the various PIPsthat interconnect the CLABs. Each PIP typically includes a switch suchas a single pass transistor. The state of conduction, i.e. whether theswitch is opened or closed, is controlled by application of the controlsignals discussed above to a transistor control terminal, e.g. a gate.The state of the control signal stored in a latch determines whether apass transistor (PIP) is turned on or off, thereby opening or closing apath in the field programmable interconnect, as described in U.S. Pat.No. 5,581,198, the contents of which is incorporated by reference. Invarious embodiments, single molecule magnet (SMM) cells or singlemolecule optical storage cells as described in this application are usedto implement PIPs to increase number of PIPs that can be fit onto anintegrated circuit. In one embodiment, the SMMs replace RAMs coupled toswitches or pass transistors as described in the '198 patent. In anotherembodiment, the SMMs operate both as storage and switch, namely that asprogrammed, the SMMs are positioned in predetermined positions that linkvarious interconnected segments to program the field programmable array.In yet another embodiment, the PIP can be a nanobridge. The nanobridgeincludes a thin layer of copper sulfide that separates a copperelectrode from a titanium electrode. The copper whisker is grown anddissolved across a metal-copper sulphide-metal sandwich. When asufficient voltage is applied, copper ions migrate up through the coppersulfide dielectric, forming a nanoscale whisker that eventually connectsthe two electrodes part of the interconnect structure described above.Applying a programming voltage to the nanobridge structure causes alow-resistance conduction path to form through a dielectric material,shorting together two electrodes. Applying a reverse bias causes theions to migrate away from the titanium, in effect taking down thebridge. In one embodiment, the nano-bridge is used as a dynamicallyreconfigurable device where programming voltages are used to establishlinks between elements of the reconfigurable device. Alternatively, asolid, silver atomic-laden chalcogenide electrolyte can be used as thesandwiched layer with silver being deposited on the electrode to formthe bridge when in the on-state.

Alternatively, in place of SMMs, electric field activated switches canbe used. For example, United States Patent Application 20020114557provides a molecular system for nanometer-scale reversible electronicand optical switches, specifically, electric field-activated molecularswitches that have an electric field induced band gap change that occursvia a molecular conformation change or a tautomerization. Changing ofextended conjugation via chemical bonding change to change the band gapis accomplished by providing the molecular system with one rotatingportion (rotor) and two or more stationary portions (stators), betweenwhich the rotor is attached. The molecular system of the presentinvention has three branches (first, second, and third branches) withone end of each branch connected to a junction unit to form a “Y”configuration. The first and second branches are on one side of thejunction unit and the third branch is on the opposite side of thejunction unit. The first branch contains a first stator unit in itsbackbone, the junction unit comprises a second stator unit, and thefirst branch further contains a rotor unit in its backbone between thefirst stator unit and the second stator unit. The second branch includesan insulating supporting group in its backbone for providing a length ofthe second branch substantially equal to that of the first branch,wherein the rotor unit rotates between two states as a function of anexternally-applied field. In other embodiments, a molecule called arotaxane or a catenane trapped between two metal electrodes can beswitched from an ON state to an OFF state by the application of apositive bias across the molecule. The ON and OFF states differed inresistivity by about a factor of 100 and 5, respectively, for therotaxane and catenane.

In one embodiment, the nano-elements include nanobridge. The nanobridgeincludes a thin layer of copper sulfide that separates a copperelectrode from a titanium electrode. The copper whisker is grown anddissolved across a metal-copper sulphide-metal sandwich. When asufficient voltage is applied, copper ions migrate up through the coppersulfide dielectric, forming a nanoscale whisker that eventually connectsthe two electrodes. Applying a programming voltage between the twoelectrodes in the nanobridge structure causes a low-resistanceconduction path to form through a dielectric material, shorting togethertwo electrodes. Applying a reverse bias voltage between the twoelectrodes causes the ions to migrate away from the titanium, in effecttaking down the bridge, that is, the configuration of the nanobridgestructure is removed. In one embodiment, the nano-bridge is used as adynamically reconfigurable device where programming voltages are used toestablish links between elements of the reconfigurable device.Applications include Field Programmable Gate Array (FPGA). Thesemiconductor elements in the first layer or the spin-coatednano-elements in the second layer form a Field Programmable Gate Array.At least one of the semiconductor elements in the first layer or thenano-elements are reconfigurable.

Alternatively, a solid, silver atomic-laden chalcogenide electrolyte canbe used as the sandwiched layer with silver being deposited on theelectrode to form the bridge when in the on-state.

FIG. 3 shows another embodiment having a series chain of molecular ornano-elements 140 and a means for accessing the chain. In the embodimentshown in FIG. 3, the nano-elements 140 are resistors. The series chain140 has a plurality of two terminal molecular elements connected inseries. The series chain 140 has a first element 113, a last element115, and one or more intermediate molecular elements 112. Each of theintermediate molecular elements 112 is connected to the molecularelement adjacent to it at a node, of which node 143 is typical. Oneterminal 150 of the first molecular element is connected to a firstterminal 114. The other terminal 151 of the first molecular element 113is connected to the first intermediate molecular element at node 142.Similarly, the last molecular element 115 has one of its terminals 156connected to the adjacent intermediate molecular element at node 155.The other terminal 157 of the last element 115 is connected by theaccessing means to a second terminal 116. At least one of the terminals150 and 157 is accessible to an external circuit connected to theapparatus of the present invention. The accessing means connects aselected one of the nodes to a third terminal 118.

In one embodiment, the nano-elements are resistors. Other embodiments,however, in which the nano-elements are capacitors, inductors, or acombination of one or more of these three types of molecular elements ornano-elements will be obvious to those skilled in the art. In oneversion, each of the molecular elements provides the same impedance (forthe resistor embodiment), capacitance (for the capacitor embodiment), orinductance (for the inductor embodiment). Embodiments in which themolecular elements are of different values will also be obvious to thoseskilled in the art.

In the resistor embodiment, each element in the series chain 140 has aseries combination of two resistive elements. In one embodiment, thefirst such element is chosen to have a positive temperature coefficient,and the second such element is chosen to have a negative temperaturecoefficient. The temperature coefficients in question are selected suchthat the series or parallel combination of the two elements is aresistive element having an essentially zero temperature coefficient.

A switch 144 is provided for connecting a selected node to the terminal118. The switch 144 in turn includes a selector (not shown) to selectwhich node is to be connected, and a memory device (not shown) forstoring the identity of the selected node connected to the thirdterminal 118 and for causing the node to be reconnected to the thirdterminal 118 when power is reapplied or restored to the apparatus.

The switch 144 has a plurality of electrically controllable switches,one tied to each node in the chain 140 of which switch 120 is typical.The switch 120 can be a transistor fabricated in accordance withsemiconductor technique or a nano-transistor as discussed in this case.One terminal of each electrically controllable switch is connected to arespective one of the nodes. The other terminal of each switch isconnected in common with all other corresponding switch terminals to thethird terminal 118. Each electrically controllable switch may be closedby applying a signal to a control terminal of which terminal 137 istypical. When an electrically controllable switch is closed, the node towhich it is connected is connected to the third terminal 118. Only oneof the electrically controllable switches is closed at a given time. Inthe preferred embodiment, each electrically controllable switch is aconventional MOSFET.

A selecting means can be a binary shift register in which all of thebits are set to “0” except for one bit which contains a “1” could alsobe used. Each bit in the shift register would be connected to acorresponding electrically controllable switch control terminal. In thisembodiment, the choice of which node is connected to the third terminal118 would be made by shifting the contents of the register either up ordown by signals on appropriate control lines. The state of the shiftregister could be stored in an electrically reprogrammable memory whichhas one bit corresponding to each of the bits in the shift register.

In another embodiment, the nano-elements are transistors or diode. Asdiscussed in US Patent Publication 20030178617, the disclosure of whichis incorporated hereof by reference, a self-aligned carbon-nano tubefield effect transistor semiconductor device is fabricated. The devicecomprises a carbon-nano tube deposited on a substrate, a source and adrain formed at a first end and a second end of the carbon-nano tube,respectively, and a gate formed substantially over a portion of thecarbon-nano tube, separated from the carbon-nano tube by a dielectricfilm. Alternatively, a carbon-nano tube field effect transistorsemiconductor device is provided. The device comprises a verticalcarbon-nano tube wrapped in a dielectric material, a source and a drainformed on a first side and a second side of the carbon-nano tube,respectively, a bilayer nitride complex through which a band strap ofeach of the source and the drain is formed connecting the carbon-nanotube wrapped in the dielectric material to the source and the drain, anda gate formed substantially over a portion of the carbon-nano tube.

In accordance with another embodiment of the present invention, thenano-elements such as transistors, capacitors, inductors and diodes, canbe provided using DNA molecules as a support structure. DNA bindingproteins are used to mask regions of the DNA as a material, such as ametal is coated onto the DNA. The present invention also providesmethods of making integrated circuits using DNA molecules as a supportstructure. Methods for making DNA based transistors, capacitors,inductors and diodes are discussed in US Patent Publication 20010044114,the disclosure of which is incorporated hereof by reference.

In one embodiment, the nano-elements can be a substantiallytwo-dimensional array made up of single-walled nano tubes aggregating(e.g., by van der Waals forces) in substantially parallel orientation toform a monolayer extending in directions substantially perpendicular tothe orientation of the individual nano tubes. Such monolayer arrays canbe formed by conventional techniques employing “self-assembledmonolayers” (SAM) or Langmiur-Blodgett films. nano tubes are bound to asubstrate having a reactive coating (e.g., gold). Typically, SAMs arecreated on a substrate which can be a metal (such as gold, mercury orITO (indium-tin-oxide)). The molecules of interest, here the SWNTmolecules, are linked (usually covalently) to the substrate through alinker moiety. The linker moiety may be bound first to the substratelayer or first to single-wall nano tubes (“SWNT”) molecule (at an openor closed end) to provide for reactive self-assembly. Langmiur-Blodgettfilms are formed at the interface between two phases, e.g., ahydrocarbon (e.g., benzene or toluene) and water. Orientation in thefilm is achieved by employing molecules or linkers that have hydrophilicand lipophilic moieties at opposite ends.

In one embodiment the SAM, or two-dimensional monolayer, described abovemay be the starting template for preparing a three dimensionalself-assembling structures. Where the end caps of the component SWNTmolecules have mono-functional derivatives the three-dimensionalstructure will tend to assemble in linear head-to-tail fashion. Byemploying multi-functional derivatives or multiple derivatives atseparate locations it is possible to create both symmetrical and nonsymmetrical structures that are truly three-dimensional.

Carbon nano tubes in material obtained according to the foregoingmethods may be modified by ionically or covalently bondingfunctionally-specific agents (FSAs) to the nano tube. The FSAs may beattached at any point or set of points on the fullerene molecule. TheFSA enables self-assembly of groups of nano tubes into geometricstructures. The groups may contain tubes of differing lengths and usedifferent FSAs. Self-assembly can also occur as a result of van derwaals attractions between derivitized or underivitized or a combinationof derivitized and underivitized fullerene molecules. The bondselectivity of FSAs allow selected nano tubes of a particular size orkind to assemble together and inhibit the assembling of unselected nanotubes that may also be present. Thus, in one embodiment, the choice ofFSA may be according to tube length. Further, these FSAs can allow theassembling of two or more carbon nano tubes in a specific orientationwith respect to each other.

By using FSAs on the carbon nano tubes and/or derivitized carbon nanotubes to control the orientation and sizes of nano tubes which areassembled together, a specific three-dimensional structure can be builtup from the nano tube units. The control provided by the FSAs over thethree-dimensional geometry of the self assembled nano tube structure canallow the synthesis of unique three-dimensional nano tube materialshaving useful mechanical, electrical, chemical and optical properties.The properties are selectively determined by the FSA and the interactionof and among FSAs.

Properties of the self-assembled structure can also be affected bychemical or physical alteration of the structure after assembly or bymechanical, chemical, electrical, optical, and/or biological treatmentof the self-assembled fullerene structure. For example, other moleculescan be ionically or covalently attached to the fullerene structure orFSAs could be removed after assembly or the structure could berearranged by, for example, biological or optical treatment. Suchalterations and/or modifications could alter or enable electrical,mechanical, electromagnetic or chemical function of the structure, orthe structure's communication or interaction with other devices andstructures.

In yet another embodiment, a nanotube wired OR logic can be implemented.The upper nanotubes or nanowires IN0, IN1, IN2, IN3 contact lowernanotube, thus forming a plurality of low resistance PN-type junctionsdiscussed in US Application Serial No. 20030200521, the content isincorporated by reference. Alternatively, a programmable diode OR arraywith nanotubes can be used. The OR devices do not produce gain.Therefore, restoring logic performing signal restoration is needed toprovide gain, either at the microscale or at the nanoscale level. Signalrestoration allows high signals to be driven higher and low signals tobe driven lower, in order to allow an arbitrary number of devices to becascaded together and a logical distinction between a low logical valueand a high logical value to be maintained. Therefore, signal restorationhelps protecting the circuit against noise and allows arbitrary circuitcomposition. Restoring logic is provided at the nanoscale level in orderto allow the output of a first stage to be used as input for a secondstage, making it possible to compute through an arbitrary number oflogic stages without routing the signal to non-nanoscale (e.g.,microscale) wires. Using the FET junctions, NMOS-like inverters, NAND,AND, NOR, or OR logic can be built. In a first scenario (pull-up), allinputs IN0, . . . , INM-1 of the FETs are low. As a consequence, thereis conduction through all the FETs formed at the wire crossings (noevacuation of charge). Since there is conduction through all the FETsand the top end of the series of FETs is connected to a power supplydriven to a high voltage, the wire can be pulled up to the high voltageof the power supply. The output is now high. In a second scenario(pull-down), one of the inputs IN0, . . . , INM-1 is high. Ideally,there is no conduction through the portion of the wire under this FET.This breaks the path from the high voltage supply to the output regionof the wire. In absence of current flow, the output cannot be pulled upto the high voltage. The static pulldown is always weakly enabled. If itis not pulling against a strong connection to the high voltage supply,as in the previous scenario, the weak static pulldown will be able topull the output down to a low voltage level. The output of the FET isnow low. Alternatively, restoration at the nanoscale level could also beobtained by means of precharge logic structures. In the simplest case,the static pull-down in the NOR is replaced with a precharge gate.Alternatively, the single pull-down line could be microscale instead ofnanoscale. Additionally, an additional microscale input to disable thepull-up could be added. Operation is started by driving the new pull-upline (the additional input) to a high value (disabling current flow tothe power supply), and enabling the pull-down precharge line by drivingit to a low value. This will allow the output to charge to a low value.After the output is charged to a low value, the pull-down is disabled.The output will remain at the low value for which it is now precharged.Subsequent to this, the new pull-up line is enabled. If all of theinputs are low, conduction is allowed to the power supply and the outputcan be pulled up. If one or more of the inputs are high, there is nosuch path and the output remains at a low voltage level. Thus, thedevice continues to perform its NOR function. Alternate stages will usecomplementary precharge phases, in order not to release the pull-upenable line while the inputs to a stage are still precharging and havenot been allowed to evaluate.

Nano Antenna

Examples of useful electric properties of the above describedself-assembled geometric structure include: operation as an electricalcircuit, a specific conductivity tensor, a specific response toelectromagnetic radiation, a diode junction, a 3-terminal memory devicethat provides controllable flow of current, a capacitor forming a memoryelement, a capacitor, an inductor, a pass element, or a switch.

The geometric structure may also have electromagnetic properties thatinclude converting electromagnetic energy to electrical current, anantenna, an array of antennae, an array that produces coherentinterference of electromagnetic waves to disperse those of differentwavelength, an array that selectively modifies the propagation ofelectromagnetic waves, or an element that interacts with optical fiber.

In the present invention, such antenna is referred as nano antenna. Awireless communication device 400 including such an nano antenna 430 isshown in FIG. 4. The wireless communication device 400 include aprocessor core 410 that is fabricated using conventional semiconductorprocesses such as CMOS. The processor 411 can include one or morecentral processor units (CPUs), one or more digital signal processors(DSPs), and Application Specific Integrated Circuits (ASICs). Thememories 412 can include dynamic random access memory (DRAM), Read Onlymemory (ROM), and flash memory. The controller 413 controls thetransceiver 420 and the nano antenna 430 to enable it to transmit andreceive wireless signals at different frequencies.

The processor core 410 can be fabricated using nano elements such astransistors, diodes, capacitors, resistors, as described above or usingconventional semiconductor processes on a semiconductor substrate.

In accordance with the present invention, the electromagnetic propertiesof the nano 440 antenna can be selectively determined by the FSA and theinteraction of and among FSAs. For example, the lengths, location, andorientation of the molecules can be determined by FSAs so that anelectromagnetic field in the vicinity of the molecules induceselectrical currents with some known phase relationship within two ormore molecules. The spatial, angular and frequency distribution of theelectromagnetic field determines the response of the currents within themolecules. The currents induced within the molecules bear a phaserelationship determined by the geometry of the array. In addition,application of the FSAs could be used to facilitate interaction betweenindividual tubes or groups of tubes and other entities, whichinteraction provides any form of communication of stress, strain,electrical signals, electrical currents, or electromagnetic interaction.This interaction provides an “interface” between the self-assembled nanostructure and other known useful devices.

Choice of FSAs can also enable self-assembly of compositions whosegeometry imparts useful chemical or electrochemical properties includingoperation as a catalyst for chemical or electrochemical reactions,sorption of specific chemicals, or resistance to attack by specificchemicals, energy storage or resistance to corrosion.

Examples of biological properties of FSA self-assembled geometriccompositions include operation as a catalyst for biochemical reactions;sorption or reaction site specific biological chemicals, agents orstructures; service as a pharmaceutical or therapeutic substance;interaction with living tissue or lack of interaction with livingtissue; or as an agent for enabling any form of growth of biologicalsystems as an agent for interaction with electrical, chemical, physicalor optical functions of any known biological systems.

FSA assembled geometric structures can also have useful mechanicalproperties which include but are not limited to a high elastic tomodulus weight ratio or a specific elastic stress tensor. Opticalproperties of geometric structures can include a specific opticalabsorption spectrum, a specific optical transmission spectrum, aspecific optical reflection characteristic, or a capability formodifying the polarization of light.

Self-assembled structures, or fullerene molecules, alone or incooperation with one another (the collective set of alternatives will bereferred to as “molecule/structure”) can be used to create devices withuseful properties. For example, the molecule/structure can be attachedby physical, chemical, electrostatic, or magnetic means to anotherstructure causing a communication of information by physical, chemical,electrical, optical or biological means between the molecule/structureand other structure to which the molecule/structure is attached orbetween entities in the vicinity of the molecule/structure. Examplesinclude, but are not limited to, physical communication via magneticinteraction, chemical communication via action of electrolytes ortransmission of chemical agents through a solution, electricalcommunication via transfer of electronic charge, optical communicationvia interaction with and passage of any form with biological agentsbetween the molecule/structure and another entity with which thoseagents interact.

Fullerene nano tubes can be used to replace the more traditionalconductive elements of an antenna. For example, an (m,n) tube inconjunction with other materials can be used to form a Schottky barrierwhich would act as a light harvesting antenna. In one embodiment, a(10,10) tube can be connected via sulfur linkages to gold at one end ofthe tube and lithium at the other end of the tube forming a naturalSchottky barrier. Current is generated through photo conductivity. Asthe (10,10) tube acts like an antenna, it pumps electrons into oneelectrode, but back flow of electrons is prevented by the intrinsicrectifying diode nature of the nano tube/metal contact.

In forming an antenna, the length of the nano tube can be varied toachieve any desired resultant electrical length. The length of themolecule is chosen so that the current flowing within the moleculeinteracts with an electromagnetic field within the vicinity of themolecule, transferring energy from that electromagnetic field toelectrical current in the molecule to energy in the electromagneticfield. This electrical length can be chosen to maximize the currentinduced in the antenna circuit for any desired frequency range. Or, theelectrical length of an antenna element can be chosen to maximize thevoltage in the antenna circuit for a desired frequency range.Additionally, a compromise between maximum current and maximum voltagecan be designed. A Fullerene nano tube antenna can also serve as theload for a circuit. The current to the antenna can be varied to producedesired electric and magnetic fields. The length of the nano tube can bevaried to provide desired propagation characteristics. Also, thediameter of the antenna elements can be varied by combining strands ofnano tubes. Further, these individual nano tube antenna elements can becombined to form an antenna array. The lengths, location, andorientation of the molecules are chosen so that electrical currentswithin two or more of the molecules act coherently with some known phaserelationship, producing or altering an electromagnetic field in thevicinity of the molecules. This coherent interaction of the currentswithin the molecules acts to define, alter, control, or select thespatial, angular and frequency distributions of the electromagneticfield intensity produced by the action of these currents flowing in themolecules. In another embodiment, the currents induced within themolecules bear a phase relationship determined by the geometry of thearray, and these currents themselves produce a secondary electromagneticfield, which is radiated from the array, having a spatial, angular andfrequency distribution that is determined by the geometry of the arrayand its elements. One method of forming antenna arrays is theself-assembly monolayer techniques discussed above.

In another embodiment of the present invention, nano wires can be formedto provide the resonant circuit in the nano antenna 430. The orientationof the nano wires can be controlled to maximize the reception signalstrengths of the wireless communication device 400. Methods of orientingnanowires include the use of mask based processes alone or incombination with flow based alignment of the nanowires to provideoriented and positioned nanowires on surfaces. The populations ofnanowires can also be controlled. Details of the control of nanowireorientation and population are discussed in US Patent Publication20030186522, the disclosure of which is incorporated hereof byreference.

In accordance with the present invention, a plurality of equivalent nanocircuits at different orientations are provided in the nano antenna 430.The orientation of the nano circuits are disposed such that wirelesssignals can be received at high strength at any orientation of thewireless communication device 400 relative to the field propagationdirection of the incoming wireless wave.

In another embodiment, a plurality of nano tubes can be connected bynano switches 431 in a serial circuit to provide the nano antenna 430.The electrical lengths of the circuit and thus the resonant frequenciescan be configured by turning on and off different combinations of thenano switches 431, depending on the required frequencies of varioustelecommunication protocols. Communications standards and protocolssupported by the processor core 410, the transceiver core 420, and nanoantenna 430 include for example Global System for Mobile Communications(GSM), General Packet Radio Service (GPRS), Bluetooth, IEEE802.11 etc.

Fullerene molecules can be used to replace traditional electricallyconducting elements. Thus fullerene molecules or self-assembledfullerene groups can be the basis of electrical circuits in which themolecule transfers electrical charge between functional elements of thecircuit which alter or control the flow of that charge or objects inwhich the flow of electrical current within the object performs someuseful function such as the redistribution of the electric field aroundthe object or the electric contact in a switch or a response of theobject to electromagnetic waves. As an example, nano tubes can also beself-assembled to form a bridge circuit to provide full waverectification. This device can include four nano tubes, each forming anedge of a square, and four buckyballs, one buckyball would be located ateach corner of the square. The buckyballs and nano tubes can bederivitized to include functionally specific agents. The functionallyspecific agents form linkages connecting the buckyballs to the nanotubes and imparting the required geometry of the bridge. A fullerenediode can be constructed through the self-assembly techniques describedabove. The diode can be composed of two bucky tubes and a bucky capsule.The bucky capsule can also be derivitized to form a zwiterrion. Forexample, the bucky capsule can include two positive groups, such as thetriethyl amine cation and two negative groups, such as CO₂—anion. In oneembodiment, each end of the bucky capsule is connected to a (10, 10)bucky tube by a disulfide bridge. Thus, sulfur serves as thefunctionally-specific agent.

Various molecules or nano-elements can be coupled to one or moreelectrodes in a layer of an IC substrate using standard methods wellknown to those of skill in the art. The coupling can be a directattachment of the molecule to the electrode, or an indirect attachment(e.g. via a linker). The attachment can be a covalent linkage, an ioniclinkage, a linkage driven by hydrogen bonding or can involve no actualchemical attachment, but simply a juxtaposition of the electrode to themolecule. In some preferred embodiments, a “linker” is used to attachthe molecule(s) to the electrode. The linker can be electricallyconductive or it can be short enough that electrons can pass directly orindirectly between the electrode and a molecule of the storage medium.The manner of linking a wide variety of compounds to various surfaces iswell known and is amply illustrated in the literature. Means of couplingthe molecules will be recognized by those of skill in the art. Thelinkage of the storage medium to a surface can be covalent, or by ionicor other non-covalent interactions. The surface and/or the molecule(s)may be specifically derivatized to provide convenient linking groups(e.g. sulfur, hydroxyl, amino, etc.). In one embodiment, the moleculesor nano-elements self-assemble on the desired electrode. Thus, forexample, where the working electrode is gold, molecules bearing thiolgroups or bearing linkers having thiol groups will self-assemble on thegold surface. Where there is more than one gold electrode, the moleculescan be drawn to the desired surface by placing an appropriate (e.g.attractive) charge on the electrode to which they are to be attachedand/or placing a “repellant” charge on the electrode that is not to beso coupled.

Nano Memory Devices

In yet another embodiment shown in FIG. 5, the nano-elements can be anarray of single-molecule magnets (SMMs). In one embodiment, arrays ofSMMs can be used in combination with semiconductor structures to replacesolid state memory systems or alternatively the SMMs can be deposited ona disk platter to achieve high density disk drive. The SMM molecules canbe used for spin-based molecular electronics devices as well.

Single molecule magnets (SMMs) are nano magnets that consist of a coreof strongly exchange-coupled transition metal ions with a large magneticmoment per molecule. SMM form crystals that are monodisperse—everymolecule in a crystal has the same spin, orientation, magneticanisotropy and atomic structure. Hence magnetic measurements of acrystal can be used to characterize the properties of individualmagnetic molecules. SMMs have magnetic anisotropy that favors themagnetic moment to be either up or down with respect to the easy axis.The energy barrier between up and down states (the anisotropy barrier)leads to magnetic hysteresis and to magnetic bistability for magneticdata storage. Transitions between up and down magnetic states can occurby thermal activation and quantum tunneling. Due to the discrete energyspectrum, transitions are favored when up and down energy levels are inresonance, or, more precisely, have an anticrossing. These resonancesonly occur at certain magnetic fields. Each SMM has a fixed molecularsize and shape, and unlike normal magnets, the properties of the SMM aredue to intrinsic molecular properties. The SMM gains its properties fromthe large potential energy barrier between the spin “up” and spin “down”states. One exemplary SMM is Mn₁₂O₁₂(O₂CMe)₁₆(H₂O).2MeCO₂H.4H₂O, withS=10, and its related Mn complexes. Other classes of in the Mn family ofmolecules, Mn₄O₃ complexes, can also be used as SMMs.

The SMMs are made from transition metal clusters exhibiting magneticbistability. The SMMs possess a high-spin ground state (S), which, whencombined with a negative axial zero-field splitting (D<0), leads to anenergy barrier for spin reversal. The SMMs incorporate oxo-basedbridging ligands that mediate the magnetic exchange coupling betweenmetal centers. In another embodiment having clusters with larger spinreversal barriers, cluster systems formed by replacing Cr^(III) withMo^(III) in the linear cluster[(Me₃tacn)₂-(cyclam)NiCr₂(CN)₆]₂+(Me₃tacn)N,N′,N″-trimethyl-1,4,7-triazacyclononane;cyclam=1,4,8,11-tetraazacyclotetradecane) or an analogous substitutionin the trigonal prismatic cluster [(Me₃tacn)₆MnCr₆(CN)₁₈]^(2+,3c)bearing a higher spin ground state of S=3/2 can be used as acyano-bridged single-molecule magnet.

As shown in FIG. 5, an SMM memory device includes a memory cell array200 constructed over a substrate such as the substrate includes asilicon-on-insulator (SOI) wafer. In the memory cell array 200, firstsignal electrodes (chemical structure lines or word lines) 212 forselecting rows and second signal electrodes (bit lines) 216 forselecting columns are arranged to intersect at right angles. The firstsignal electrodes may be the bit lines and the second signal electrodesmay be the chemical structure lines, differing from this example. An SMMlayer 214 is disposed at least between the first signal electrodes 212and the second signal electrodes 216. Therefore, memory cells 220, eachof which includes an SMM, are formed at intersections between the firstsignal electrodes 212 and the second signal electrodes 216. A peripheralcircuit section 260 including a peripheral driver circuit forselectively allowing information to be written into or read from thememory cells and an amplifier circuit which for reading the informationis also formed. The peripheral circuit section 260 includes a firstdriver circuit 250 for selectively controlling the first signalelectrodes 212, a second driver circuit 252 for selectively controllingthe second signal electrodes 216, and a signal detecting circuit (notshown) such as a sense amplifier, for example.

As specific examples of the peripheral circuit section 260, a Y gate, asense amplifier, an input-output buffer, an X address decoder, a Yaddress decoder, and an address buffer can be given. A write line isformed near the SMM cell 220 and the write line is used for writing andinverting magnetization of nano-magnetic material layer of the SMM cell220 by a current flow, as the magnetization is magnetic information.

The peripheral circuit section 260 may be formed by MOS transistorsformed on a substrate (single crystal silicon substrate, for example).In the case where the substrate is formed of a single crystal siliconsubstrate, the peripheral circuit section 260 can be integrated on thesame substrate as the memory cell array 200. The SMMs are formed last byspin-coating a solution containing self-assembled SMMs on a wafer afterthe wafer has been processed and devices are formed using conventionalsemiconductor fabrication techniques. Conventional semiconductorstructures are formed as is conventional. During the next to the lastconventional step, gold electrodes are formed. Then a resist layer isformed over the last layer, and selective etching is performed to exposethe gold electrodes. A solution containing the SMMs is spin-coated ontop, where the SMMs self-assemble.

Writing to the bit is accomplished by applying a polarized voltage pulsethrough a nanocircuit element. A positive pulse will pull the SMM and anegative pulse will push the SMM. The bistable nature of the bit willresult in the SMM staying in the positioned end when the pulse isremoved since that is where the energy is lowest. To read the bit,another nanocircuit element is biased with a VREAD voltage. If the SMMis present in the detection end, it supplies the necessary energy levelsfor current to resonantly tunnel across the junction to the groundvoltage (in a fashion analogous to a resonant tunneling diode) resultingin a first stable state being read. If the SMM is not present in thedetection end, the energy levels are shifted out of resonance and thecurrent does not tunnel across the junction and a second stable state isread. Other forms of read/write structure (e.g., microactuators) can beemployed as will be recognized by one skilled in the art.

A memory device can be constructed using either a two- orthree-dimensional array of the SMMs. Because the SMMs are molecular insize, a dense memory chip can be fabricated. Further, the wiring widthand the area of each cell is reduced. The switching electric field canbe reduced by using the SMM memory cell and write current necessary forwriting a magnetization invert may be reduced, whereby power consumptionbeing restrained and switching being carried out at high speed. The nanocoercive force is small and the switching magnetic field is small. Whenthe nano-device is used as a memory cell of a magnetic memory, thecurrent of a write wiring for generating a magnetic field necessary forinverting magnetization can be reduced. Therefore, according to themagnetic memory forming the memory cell by nano-magnets, a highlyintegrated formation can be performed, the power consumption is reduced,and the switching speed can be made faster.

The molecular memory such as SMM memory is used as on-chip data oroff-chip storage device for a processor chip. In one embodiment, thememory system organization is a multi-level memory hierarchy. Acombination of a small, low-latency level one (L1) memory backed by ahigher capacity, yet slower, L2 memory and finally by main memoryprovides the best tradeoff between optimizing hit time and miss time.Different molecular memory arrays with differing speed and sizerequirements can be deployed in a computer system. For example, a highspeed static RAM can be used as L1 memory, while a high speed highdensity nano memory array can be used as L2 memory and low speed nanomemory array can be used as regular memory. In one system on a chip,processor logic and cache is implemented using traditional semiconductorstructure, and a large main memory array is provided on chip usingmolecular memory. Finally, nano-head disk drive can be used as long termdata storage devices.

Nano Disk Drive

Yet another embodiment is an embodiment in which the SMMs are applied toa magnetic head. FIG. 6A is a perspective view of a nano-magnetic headassembly mounted with an SMM head. An actuator arm 301 is provided witha hole for being fixed to a fixed shaft inside of a magnetic diskapparatus and is provided with a bobbin portion for holding a drive coil(not illustrated) and the like. A suspension 302 is fixed to one end ofthe actuator 301. A front end of the suspension 302 is wired with a leadwire 304 for writing and reading signals, one end of the lead wire 304is coupled with respective electrode of a nano-magnetic head 305 mountedon a head slider 303, and the other end of the lead wire 304 isconnected to an electrode pad 306. The nano-head 305 is fabricated usingthin-film type substrate, with spin-coating of the SMM elements at thelast stages of head manufacture.

The nano-head 305 has one or more nano sub-heads so that it can accessinformation serially or in parallel for improved data throughput. Inaddition, error correction codes can be encoded and decoded on thenano-head. Further, each of the sub-heads can be part of a RAID array.The nano-head 305 provides data used for standard RAID levels including1, 3, and 5 or combinations of two other RAID levels. For example, inRAID 1+0 (also called RAID 10), multiple RAID 1 pairs are striped forfaster access; and in RAID 15, two RAID 5 arrays are mirrored for addedreliability.

FIG. 6B is a perspective view of an inner structure of a magnetic diskapparatus (magnetic information reproducing apparatus) mounted with themagnetic head assembly of FIG. 6A. A nano-magnetic disk 311 is mountedon a spindle 312 and is rotated by a motor (not illustrated) respondingto a control signal from a control portion of a drive apparatus (notillustrated). The nano-magnetic disk 311 has a surface that is processedusing thin film deposition with a spin-coat of the self-assembled SMMslate in fabrication of the disk 311. The actuator arm 301 is fixed to afixed shaft 313 for supporting the suspension 302 and the head slider303 at the front end thereof. When the magnetic disk 311 is rotated, asurface of the head slider 303 opposed to the disk 311 is held in afloating state from a surface of the magnetic disk 311 by apredetermined amount, thereby reproducing the magnetic information ofthe magnetic disk. At another end of the actuator arm 301, a chemicalcoil motor 314 is provided and includes a type of a linear motor. Thechemical coil motor 314 includes a drive coil (not illustrated) wound upto the bobbin portion of the actuator arm 301 and a magnetic circuitincluding a permanent magnet and an opposed yoke arranged to be opposedto each other to interpose the coil. The actuator arm 301 is supportedby ball bearings (not illustrated) provided at two upper and lowerlocations of the fixed shaft 313 and can freely be slidingly rotated bythe chemical coil motor 314.

Nano-Optical Dram

In yet another embodiment, the nano-elements can be an array of opticalstorage molecules (OSMs). In one embodiment, arrays of OSMs can be usedin combination with semiconductor structures to replace solid statememory systems or alternatively the OSMs can be deposited on a diskplatter to achieve high density disk drive. The OSM molecules can beused for spin-based molecular electronics devices as well.

The OSMs convert energy patterns into electronic digital signals byexposing an image plate having OSMs supported by a matrix to an energypattern. The energy pattern can be provided by a plurality of opticalsignals output from a bundle of optical fibers of optical circuitry. Theapplications include telecommunication and parallel optical computing. Aplurality of energy patterns recorded by the array of OSMs in electronicsignals can be considered as snapshots of optical signals which can beread as optical signals or electronic signals.

In one embodiment, the OSM can be a nanophase storage luminescencematerial of the general formula X/Y, wherein X is at least one guest andY is a host. The host can be selected from the group consisting oforganic, inorganic, glass, crystalline, non-crystalline, porousmaterials or combinations thereof. The host can be semiconductingnanoparticles such as insulating nanoparticles, conductingnanoparticles, and combinations thereof. The semiconductor nanoparticlecan be sulfide, telluride, selenide, or oxide semiconductors. Thesemiconductor nanoparticle is selected from the group of Zn_(x)S_(y),Zn_(x)Se_(y), Zn_(x)Te_(y), Cd_(x)S_(y), Cd_(x)Se_(y), Cd_(x)Te_(y),Pb_(x)S_(y), Pb_(x)Se_(y), Pb_(x)Te_(y), Mg_(x)S_(y), Ca_(x)S_(y),Ba_(x)S_(y) and Sr_(x)S_(y), wherein 0<x≦1, 0<y≦1. The semiconductornanoparticle can be ZnS. The semiconductor nanoparticle can also berepresented by the general formula (M_(1-z)N_(z))_(x)A_(1-y)B_(y),wherein M=Zn, Cd, Pb, Ca, Ba, Sr, Mg; N═Zn, Cd, Pb, Ca, Ba, Sr, Mg; A=S,Se, Te, O; B═S, Se, Te, O; 0<x≦1, 0<y≦1, 0<z≦1). The semiconductornanoparticle can also be Zn_(0.4)Cd_(0.4)S.

The writing of optical signals involves the conversion of opticalsignals to electronic states via photon induced electronic excitations.As discussed in Application Serial No. 20030064532, nano particle energystructure can be modified via quantum size confinement. When electronsand holes are produced in nano particles by excitation, the electronsand holes may de-excite or relax to the lowest excited states andrecombine to give luminescence. They also may be trapped by electron orhole traps at the surfaces, interfaces, or/and in the surroundingmatrix. The electrons or holes at traps are in a metastable state.

The read-out of the recorded electronic data converted from opticalsignals can be achieved by several mechanisms. 1) When stimulated bylight or by heat some electrons or holes may be released and go back tothe nano particles, recombining to provide luminescence—i.e.,photostimulated luminescence (PSL) or thermoluminescence. Light energyis provided to optically stimulate the photostimulated luminescence nanoparticles. The nano particles release the stored energy and provideluminescence due to electron-hole recombination; and converting theluminescence into digital signals indicative of the energy pattern. Thestimulating light or heat energies can be applied uniformly to the arrayof OSMs and detecting the PSL and thermoluminescence by a 2D opticalsensor. 2) Alternatively, the recombination and luminescence of thestored electrons and holes in the energy pattern can also be stimulatedby sweeping electric voltage pulses along the word lines and bit lines.The detection of the stimulated luminescence signals include only asingle or 1D array of optical detectors. 3) Finally, the storedelectrons and holes from the exposed energy pattern can be read outelectronically as in conventional memory devices using the electroniccircuitry in the memory cell array as described below. Transistors canbe provided to convert the stored charge to voltage signals. Additionalconductive lines connecting to the collector, the emitters, the gatescan be provided to facilitate the readouts. The invention device issimilar to electrically erasable programmable read-only memory (EEPROM)devices with additional optical writing (via 2D optical pattern)capabilities.

An exemplified architecture of the OSM memory device is illustrated inFIG. 5. The OSM memory device includes a memory cell array constructedover a substrate and the substrate includes a silicon-on-insulator (SOI)wafer. In the memory cell array, first signal electrodes (word lines)for selecting rows and second signal electrodes (bit lines) forselecting columns are arranged to intersect at right angles. The firstsignal electrodes may be the bit lines and the second signal electrodesmay be the chemical structure lines, differing from this example. An OSMlayer is disposed at least between the first signal electrodes and thesecond signal electrodes. Therefore, memory cells, each of whichincludes an OSM, are formed at intersections between the first signalelectrodes and the second signal electrodes. A peripheral circuitsection (including a peripheral driver circuit for selectively allowinginformation to be written into or read from the memory cells) and anamplifier circuit which for reading the information is also formed. Theperipheral circuit section includes a first driver circuit forselectively controlling the first signal electrodes, a second drivercircuit 252 for selectively controlling the second signal electrodes,and a signal detecting circuit such as a sense amplifier, for example.

The OSMs are formed last by spin-coating a solution containingself-assembled OSMs on a wafer after the wafer has been processed anddevices are formed using conventional semiconductor fabricationtechniques. Conventional semiconductor structures are formed as isconventional. During the next to the last conventional step, goldelectrodes are formed. Then a resist layer is formed over the lastlayer, and selective etching is performed to expose the gold electrodes.A solution containing the OSMs are spin-coated on top, where the OSMsself-assemble. Writing to the bit is accomplished by applying a tightlyfocused light emitter that can be a nanocircuit element. To read thebit, another nanocircuit element such as a light detector detectswhether the optical DRAM cell is on or off based on the stored lightenergy. If the OSM is on, it supplies the necessary energy levels forcurrent to resonantly tunnel across the junction to the ground voltage(in a fashion analogous to a resonant tunneling diode) resulting in afirst stable state being read. If the OSM is off, the energy levels areshifted out of resonance and the current does not tunnel across thejunction and a second stable state is read. Other forms of read/writestructure (e.g., microactuators) can be employed as will be recognizedby one skilled in the art.

A memory device can be constructed using either a two- orthree-dimensional array of the OSMs. Because the OSMs are molecular insize, a dense memory chip can be fabricated. Further, the wiring widthand the area of each cell is reduced. The switching light field can bereduced by using the OSM memory cell and write current necessary forwriting an optical invert may be reduced, whereby power consumptionbeing restrained and switching being carried out at high speed. Themolecular memory such as OSM memory is used as on-chip data or off-chipstorage device for a processor chip. In one embodiment, the memorysystem organization is a multi-level memory hierarchy. A combination ofa small, low-latency level one (L1) memory backed by a higher capacity,yet slower, L2 memory and finally by main memory provides the besttradeoff between optimizing hit time and miss time. Different molecularmemory arrays with differing speed and size requirements can be deployedin a computer system. For example, a high speed static RAM can be usedas L1 memory, while a high speed high density nano optical DRAM arraycan be used as L2 memory and low speed nano memory array can be used asregular memory. In one system on a chip, processor logic and cache isimplemented using traditional semiconductor structure, and a large mainmemory array is provided on chip using molecular memory. Finally,nano-head disk drive can be used as long term data storage devices.

Nano Optical Interconnect

In a high speed multi-chip module (MCM) environment, chip-to-chipconnections are usually made using bond wires, with microstrip lines onthe MCM substrate used to interconnect chips that are farther apart.Presently, electrical bond wires are used to interconnect microchips.Using the electrical wires has serious drawbacks. The electrical wiresare sensitive to electromagnetic interference and themselves create suchinterference which poses especially serious problems for distribution oftiming signals. The electrical wires must be located at the edges ofchips. Signal attenuation and phase delay depend upon the length of theelectrical wires. Thus, depending on the lengths of the electrical wiresand their locations in the module, it may be difficult to achieve equalattenuation and/or equal signal phase delay among multiple wires, ifneeded. In addition, in many cases signal bandwidths of severalGigahertz are desirable but cannot be achieved if electrical wires areused because electrical bond wires act as open antennae at highfrequencies and introduce noise coupling among the wires. For example,bond wires of 500 micrometers in length and 1 mil (0.001 inch) diametercarrying 10 milliamperes of current will produce appreciable (100millivolts or more) coupling or cross-talk at 10 Gigahertz even whenthey are spaced several pitch distances apart, a typical pitch being 100to 150 micrometers. This effect will substantially limit the maximumspeed of a typical MCM module having hundreds of bond wires from severalchips. The cross-talk is even more severe when the chips are locatedfarther apart and require longer bond wires. Previously, optoelectronicdevices such as vertical-cavity lasers and photodetectors have beenbonded onto microelectronic chips to provide free-space opticalinterconnections. However, such lasers and detectors are bulky.

In one embodiment of the invention, nano optical elements such as OSMsare used with an optical waveguide to interconnect MCMs to provide anoptical interconnection system. In one embodiment, conventionalelectronics are deposited using standard semiconductor processingtechniques. Next, OSMs and light detectors are spin-coated above thesemiconductor layer and they self assemble to form transmitters orreceivers at designated locations on the MCMs. During fabrication, theMCMs are immersed in a solution that allows nano-optical interconnect(nano-lightpath) to self-assemble in 3D space between the transmittersand the receivers. The self-assembly is keyed so that specificnano-lightpaths bond between specific transmitter and receiver pairs.One type of keying uses chemical bond key encoding or DNA encoding. Thenano light fibers or other suitable light conductors to interconnect theOSMs to their respective light detectors. Lightpaths traverse severalphysical links but information traveling on a lightpath is carriedoptically from end-to-end. The system is insensitive to electromagneticinterference; needs not be located at the edges of a chip but rather canbe placed for optimal utility to the circuit function; can be given thesame or other pre-specified lengths regardless of the placement in themodule; and are capable of high signal bandwidths without causing thecross-talk problem. The optical interconnection system can furtherinclude a semiconductor region over or in the substrate. An electroniccircuit can be formed conventional semiconductor techniques. Theelectronic circuit controls or monitors the interconnection of theoptical signals.

In another embodiment for wide area networking, the system performswavelength routing, which is a form of circuit switching. Inwavelength-routed networks, a lightpath, which is an end-to-end opticalcommunication connection, is established before data can be sent. Suchlightpaths are called “wavelength-routed” because each uses a dedicatedwavelength channel on every link along a physical path, and hence, oncedata is transmitted on a specific wavelength by its source, how the datawill be routed (or switched) at the intermediate nodes will bedetermined by the “color” of the wavelength only. Optical packetswitching (OPS) is similar to traditional electronic packet switching,except for that payload (i.e., data) will remain in optics, while itsheader may be processed electronically or optically. In one embodiment,the above optical random access memory performs optical buffering.Optical burst switching (OBS) is a technique for transmitting bursts oftraffic through an optical transport network by setting up a connectionand reserving resources end to end for the duration of a burst. OBS is away to achieve a balance between the coarse-grained wavelength routingand fine-grained optical packet switching.

In another embodiment, the system includes a nano-optical switch is anano photonic switch having N full-duplex ports, each of which canconnect to any other without OEO conversion, although the switch maystill be controlled by electronic signals. Broadly speaking, switchesrefer to devices that may be called add-drop multiplexers (ADMs),routers, and crossconnects. An add/drop multiplexer (ADM) is an opticalsystem that is used to modify the flow of traffic through a fiber at arouting node. An ADM passes traffic on certain wavelengths throughwithout interruption or opto-electronic conversions, while otherwavelengths are added or dropped, carrying traffic originating orterminating at the node. A wavelength router (WR) is a more powerfulsystem than an ADM. For each of the wavelengths it takes in a signal atan input port and routes it to a particular output port, independent ofthe other wavelengths. A WR with N input and N output ports capable ofhandling k wavelengths can be considered as k independent N X N singlewavelength switches. These switches have to be preceded by a wavelengthdemultiplexer and followed by a wavelength multiplexer to implement aWR. They are sometimes also called wavelength routing switches (WRS) orwavelength crossconnects (WXCs). Equipped with WCs, a WXC becomes awavelength interchanging switch, also known as wavelength interchangingcrossconnect (WIXC). (Note that a wavelength crossconnect (WXC) iscommonly called an optical crossconnect (OXC).

In a wavelength-routed network embodiment, nano-wavelength crossconnect(WXC) or nano-optical crossconnect (OXC) nodes are inter-connected bynano-fiber links. A lightpath is realized by allocating a wavelength oneach link on the path between the two nodes. Each link can support acertain number of wavelengths. To avoid wavelength continuityconstraint, nano-wavelength converters (WCs) are used in the network. Awavelength converter is a device that takes in data at one wavelengthand outputs it on a different wavelength. Wavelength conversion can playa significant role in improving the utilization of the availablewavelength in the network, or reducing the blocking rate for light pathrequests. The light paths can be set up and taken down upon demand.These are analogous to setting up and taking down circuits incircuit-switched networks. The key elements in the network are theoptical crossconnects (OXCs). The major components required to realizeOXCs are passive wavelength multiplexers and demultiplexers, switches,and/or wavelength converters. Depending on the functionality availableat the nodes, these networks can be classified as either static orreconfigurable. A static network does not have any switches or dynamicwavelength converters in it. A reconfigurable network, on the otherhand, contains switches and/or dynamic wavelength converters. The maindifference between the two types of networks is that the set oflightpaths that can be established between users is fixed for a staticnetwork, whereas it can be changed, by changing the states of theswitches or wavelength converters at the OXC nodes, for a reconfigurablenetwork.

Nano Optical Storage Device

In another embodiment, single molecule light sensors are used to providedata storage. The nano-elements convert energy patterns into digitalsignals by exposing an image plate having a nano particle arraysupported by a matrix to an energy pattern. The nano particle arrayformed of photostimulated luminescence nano particles which cooperate tostore energy indicative of the energy pattern. As discussed inApplication Serial No. 20030064532, nano particle energy structure canbe modified via quantum size confinement. When electrons and holes areproduced in nano particles by excitation, the electrons and holes mayde-excite or relax to the lowest excited states and recombine to giveluminescence. They also may be trapped by electron or hole traps at thesurfaces, interfaces, or/and in the surrounding matrix. The electrons orholes at traps are in a metastable state.

When stimulated by light or by heat some electrons or holes may bereleased and go back to the nano particles, recombining to provideluminescence—i.e., photostimulated luminescence (PSL) orthermoluminescence. Light energy is provided to optically stimulate thephotostimulated luminescence nano particles. The nano particles releasethe stored energy and provide luminescence due to electron-holerecombination; and converting the luminescence into digital signalsindicative of the energy pattern. As a data storage device, the writinglight can be either ultra-violet (UV) or blue or any other light havingenergy higher than the energy gap of the host materials (i.e. thewriting light is variable and will depend on the energy gap of the hostmaterial). The reading light can be visible or infrared (IR) light, thechoice of reading light is also variable and depends on the trap depthof the host material. Semiconductors such as MgS, CaS, SrS, and SrSedoped with rare earth elements such as Ce, Sm, and Eu have beenpreviously considered for optical storage and dosimetric applications.The configuration of the optical writer and optical reader are similar aCD-R or DVD-R drive and similar to the configurations in FIGS. 6A and6B. The layer of nano particles can be spin-coated over a substratesurface.

Nano Chemical Sensors

FIG. 7 is an exemplary diagram of a system having an array of nano-basedsensors. The nano-elements can be used as sensors such as Guided-OpticsIntrinsic Chemical Sensors. These sensor types are based on the factthat chemical species can affect the waveguide properties. Hence, it isnot the absorption or emission properties of an analyte that aremeasured, but rather the effect of the analyte upon the opticalproperties of the optical waveguide. More specifically, these sensorsare based on one or more of the following effects of the analyte: (a) Anincrease in the strain/stress of the coating, (b) Modification of thewaveguide temperature, (c) Attenuation of the guided light amplitude,(d) Change of the effective refractive index of the mode, (e)Modification of the polarization of the light.

In one embodiment, a sensor includes resonant nano particles embedded ina semipermeable matrix. The nano scale sensor can operate with a singlemolecule to recognize the presence of a specific short sequence in amixture of solid molecules, gaseous molecules or aqueous molecules suchas DNA or RNA molecules. The system selectively detects and identifies aplurality of chemical species by using an array of nano sensors. When atarget molecule binds to the probes (nano particles) in the sensor, theprobe molecule changes shape and alters the reflectivity of the sensor.In one embodiment, the nano particles are embedded in a carrier ormatrix. The matrix is preferably transparent to an optical samplingwavelength and not Raman active at the Stokes shifts of interest. Theoptical sample wavelength may be any suitable laser wavelength. Thematrix may be any suitable inorganic or polymeric material such asmesoporous silica. The optical sampling geometry can be as a layerdeposited onto a reflective substrate exposed to incident light.Alternatively, the optical sampling geometry can be as a cladding layerin a waveguide structure, where the Raman excitation is a result of theevanescent wave of the guided optical mode propagating in thatstructure.

The analytes of interest are exposed to the semipermeable layer, diffusethrough this layer and are adsorbed onto the surfaces of the embeddednano particles. The scattered light is modulated by the Stokes modes ofthe analyte molecules, and detection consists of spectral analysis ofthe scattered light using a standard dispersive geometry and lock-inbased photodetection. The nano particles' resonances are tuned to matcha pump laser wavelength. The nano particles can be functionalized withmolecules that exhibit a strong Raman response. A variety of candidatemolecules may be used, such as para-mercaptoaniline, which can be boundto the surface of the nano particles and which yields three strongStokes modes. Alternatively the nano particles can be embedded in amedium exhibiting a strong Raman response. The optical sampling geometrycan be a layer deposited onto a reflective substrate exposed to incidentlight. Alternatively, the optical sampling geometry can be as a layer ina waveguide structure, where the Raman excitation is a result of theevanescent wave of the guided optical mode propagating in thatstructure.

According to some embodiments, the resonant nano particles are solidmetal nano particles. The shape of the metal nano particles may beselected so as to adjust the wavelength of the resonance. Thus,contemplated shapes include spheroids, ellipsoids, needles, and thelike. Further the metal nano particles may be aggregated intomultiparticle aggregates so as to adjust the wavelength of theresonance. Still further, the metal nano particles may be embedded in amatrix material that is capable of adjusting the wavelength of theresonance. For example, the matrix may be any dielectric materialsuitable to form the core of a metal nano shell. More details on thenano shell sensor is described in Application Serial No. 20030174384,the content of which is incorporated by reference.

In one embodiment, the sensors are incorporated in an interferometer,and phase-modulated or interferometric optical sensors offer the highestsensitivity. Interferometric sensor systems typically employ theMachZehnder interferometer configuration. Other configurations such asthose of Michelson and Fabry-Perot can also be used. The interactionwith the chemical substance takes place through the evanescent waves.The physical shape of the waveguide may change. The waveguide parameterchanges due to a change in the physical dimension as well as to a changein the refractive index of the waveguide as a function of temperature.The intensity of the optical field decreases exponentially as it travelsin the waveguide. The Kramers-Kronig relationship relates the imaginarypart of the refractive index to its real part. Therefore, in attenuationmode chemical sensors, the phase of the guided mode also changes. Thephase of the guided light may change. The TM and TE mode experiencedifferent phase shifts or attenuation.

One embodiment uses polarization of the light in sensing applications.The nano-sensor consists of an integrated difference (or polarimetric)interferometer that uses only one waveguide. The waveguide is designedto have only two modes of propagation: the fundamental TE and TM modes.A small portion of the waveguide's core where it contacts the measurand(a gas or a liquid) is exposed. The propagation constant of the TE andTM modes is sensitive to the refractive index of the sample. Thedependence of each propagation constant on the refractive index of thesample is different and is dictated according to the equations for athree layer waveguide. At the output of the interferometer the lightexiting the waveguide is passed through a polarizer at 45° and into aphotodetector. After the polarizer, the waves arising from the originalTE and TM are polarized in the same direction and may interfere.

In one embodiment, shape changes in a single DNA molecule bound to eachsensor are detected and the result is compared against a database ofsubstances (for example pathogens). If a match is found, the result isdisplayed.

In another embodiment, immobilized “probe” molecules of biologicalinterest can be used. When exposed to an assay sample of interest,“target” molecules in the sample bind to the probe molecules to anextent determined by the concentration of the target molecule and itsaffinity for a particular probe molecule. If the target concentrationsare known, the affinity of the target for the different probes can beestimated simultaneously. Conversely, given the known affinities of thedifferent molecules in the target, the amounts of observed binding maybe used to estimate simultaneously the concentrations of multipleanalytes in the sample. United States Patent Application 20040002064entitled “Toxin detection and compound screening using biologicalmembrane microarrays” shows examples of the probe molecules ofbiological interest, the content of which is incorporated by reference.

In another embodiment, when a target molecule binds to the probe in thesensor, the probe molecule changes shape, and in its new conformation,pulls on the sensor. The motion of the sensor is detected usingevanescent wave scattering, which analyzes light that leaks out behind areflecting mirror. This evanescent wave is used to sense the position ofan object “beyond” the mirror. Thus, conformational changes in a singleDNA molecule at the nano meter scale are detected and the result iscompared against a database of substances (for example pathogens). If amatch is found, the result is displayed.

In another embodiment, the matrix can include Polymer Waveguide ChemicalSensors where both intrinsic and extrinsic sensing mechanisms arepresent. In this case, the optical waveguide itself is made of anano-polymer that interacts with the chemical substance. The matrix ismade from material that are able to absorb a target chemical onto thepolymer surface. By diffusing into the waveguide the chemical isseparated from the mixture. Thus, in this case, the waveguide isinvolved in both the separation process and the quantitative sensing ofthe target chemical.

In another embodiment, to increase the probing efficiency, opticalenergy inside the matrix is increased by operating the waveguide nearits cut-off, or, more conveniently, by exciting surface plasmons. Lightpropagating inside the waveguide interacts with the charge density wavesof a thin layer such as a metal like silver layer. If the guided wave'swavenumber matches that of the surface plasmon, the optical energy isabsorbed by the plasmons and is consequently dissipated. The plasmonwavenumber, in turn, depends on the conductivity and can the surfacecondition of the metallic layer. A thin sensitive polymer film isusually deposited over the metallic film which, upon absorption ofchemicals and gases, changes the plasmon wavenumber of the metallicfilm.

FIG. 7 is an exemplary diagram of an array of nano-based sensors. Asshown in FIG. 7, a sensor includes a nano-cell sensor array 300. In thesensor array 300, first signal electrodes (chemical structure lines) 312for selecting rows and second signal electrodes (bit lines) 316 forselecting columns are arranged to intersect at right angles. The firstsignal electrodes may be the bit lines and the second signal electrodesmay be the chemical structure lines, differing from this example. Anano-sensor layer 314 is disposed at least between the first signalelectrodes 312 and the second signal electrodes 316. Therefore, sensorcells 320, each of which includes a nano-sensor, are formed atintersections between the first signal electrodes 312 and the secondsignal electrodes 316. A peripheral circuit section 360 including aperipheral driver circuit for selectively allowing information to beread from the sensor cells and an amplifier circuit which for readingthe information is also formed. The peripheral circuit section 360includes a first driver circuit 350 for selectively controlling thefirst signal electrodes 312, a second driver circuit 352 for selectivelycontrolling the second signal electrodes 316, and a signal detectingcircuit (not shown) such as a sense amplifier, for example. As specificexamples of the peripheral circuit section 360, a Y gate, a senseamplifier, an input-output buffer, an X address decoder, a Y addressdecoder, and an address buffer can be given. The peripheral circuitsection 360 may be formed by MOS transistors formed on a substrate(single crystal silicon substrate, for example). In the case where thesubstrate is formed of a single crystal silicon substrate, theperipheral circuit section 360 can be integrated on the same substrateas the nano-sensor array 300. The nano-sensors are formed last byspin-coating a solution containing self-assembled nano-sensors on awafer after the wafer has been processed and devices are formed usingconventional semiconductor fabrication techniques. Conventionalsemiconductor structures are formed as is conventional. During the nextto the last conventional step, gold electrodes are formed. Then a resistlayer is formed over the last layer, and selective etching is performedto expose the gold electrodes. A solution containing the nano-sensorsare spin-coated on top, where the nano-sensors self-assemble. Finally, apermeable layer is formed above the nano-sensors to protect thenano-elements and the semiconductor elements while allowing the targetchemicals to pass through to the nano-sensors.

In one embodiment, the layer is a gas sensitive film containing orcovering nano-elements such as nano-pores. As the sensitive film isexposed to different gases or chemicals, its resistance changes. Theresistance of the film is measured by passing a small amount of currentand monitoring the voltage drop across the film. In one device forsensing air quality, the sensor's film is readily oxidized (by NO₂ orO₂) or reduced (by CO or NH₃). Upon oxidation or reduction, theelectrical resistivity (or some other physical parameter) of the matrixfilm changes and it is detected to infer the gas concentration. A heatercan be provided near the matrix to provide temperature adjustments tobetter detect gas.

In yet another embodiment, the matrix is ultrasonically activated todetect gases and chemicals. In these embodiments, a gas or chemicalsensitive nano-layer is deposited over an ultrasonic vibrator. Whengases or chemicals are absorbed by the sensitive layer, they change thelayer's mechanical properties. These mechanical changes influence thevibration amplitude and phase and can be picked up by monitoring thevibrational characteristics of the oscillator. In a microbalanceembodiment, bulk wave detection is used to detect very small massloading that occurs when minute quantities of materials are depositedover the surface of the oscillator. This method is the basis ofthickness-monitors used in evaporation systems and can detect nano gramof materials. The surface acoustic wave embodiment is even moresensitive than the microbalance embodiment since it directly detects thesurface loading. It can be used to detect simple mass loading effectsand any mechanical changes that may occur in its gas or chemicalsensitive layer. This method can detect changes as small as one part inbillion.

For example, if desired, the nano-elements can be coated with a specificcoating of interest (e.g., a ligand such as a peptide or protein, e.g.,an enzyme), chosen for its ability to bind a particular ligand bindingpartner (e.g., an antibody or receptor can bind a ligand, or canthemselves be the ligand to which ligand binding partner binds). Commonanalytes of interest for which detection is sought include glucose,cholesterol, warfarin, anthrax, testosterone, erythromycin, metabolites,pesticides, toxic molecules (e.g., formaldehyde, benzene, toluene,plutonium, etc.), ethanol (or other alcohols), pyruvate, and/or drugs.

For example, biosensors can include nano structures which capture orcomprise enzymes such as oxidases, reductases, aldehyde/ketonereductases, alcohol dehdrogenases, aldehyde oxidases, cytochrome p450s,flavin monooxygenases, monoamine oxidases, xanthine oxidases,ester/amide hydrolases, epoxide hydrolases or their substrates or whichcapture their reaction products. Signal transduction is optionallyfacilitated by use of conductive polymers, to bind compounds to the nanostructure, which facilitates electron transport to the surface of thestructure. Several such polymers are available, including, e.g.,polyaniline. It will be recognized that many of the biomolecules orother analytes to be captured (proteins, nucleic acids, lipids,carbohydrates) in the setting of a biosensor are charged, which can beused to cause them to “switch” a nano scale transistor, providing fordetection of binding of an analyte.

In other embodiments, biomolecules such as enzymes generate signals thatare detected by an array. For example, the array can include a glucoseoxidase and/or a cholesterol oxidase enzyme for the detection of glucoseor cholesterol levels in blood or other biological fluids. For example,a number of existing glucose monitoring systems exist, includingferrocene, ferricyanide and Osmium polymer mediated systems. Thesesystems generally use glucose oxidases in the process of glucosedetection. These systems are adapted to the present invention bymounting or capturing one or more analyte detection molecule (e.g.,glucose oxidase or the relevant mediator) on a nano structure ofinterest. Similarly, in a biohazard detector, a p450 or other suitableenzyme can be used to detect the presence of warfarin or anotherrelevant molecule of interest.

The binding of receptors and carbon nano tubes or biomolecules can bedetected by an electrical method or resonance method or by using an x-yfluorescent laser reader. When the method of detecting an electricalsignal is applied, the binding of receptors is detected by reading aminor change in voltage level of the carbon nano tubes occurring whenthe receptors or biomolecules are bound to the carbon nano tubes, usingan appropriate circuit. In one environment, the nano tubes ornanostructures can be any conducting or semiconducting nanostructures.In some embodiments, the nanostructures can also be nanowires, nanorods,or some other elongated nanostructures. In particular, thenanostructures can be carbon nanotubes and may be single-wall,semiconducting, carbon nanotubes. There can be any number ofnanostructures, some of which may intersect one another as they traversethe device, and some of which may traverse the device withoutintersection. A power supply applies a first voltage across thenanostructure sensing array. A first current through the nanostructuresensing array is measured with a meter. The nanostructure sensing arrayis exposed to an environment of interest. The electrical supply appliesthe same first voltage across the nanostructure sensing array and thegate voltage source applies the same first gate voltage to thesubstrate. A second current through the nanostructure sensing array ismeasured with the meter. Differences between the first current and thesecond current can be attributed to electrical changes in thenanostructure sensing array caused by interaction with an analyte.Electrical changes can be correlated to identification of particularanalytes by comparing the changes with predetermined electrical changesmade in know environments.

When the resonance detection method is applied, a nano plate structuredesigned to have a resonance frequency of a range from megaHertzs to lowgigaHertzs is irradiated with a laser diode, and the binding ofreceptors or biomolecules to the nano plate structure is opticallymeasured by detecting a reflection signal using a position detectionphotodiode. When the x-y fluorescent laser reader is used, the targetbiomolecules bound to receptors are reacted with, for example,fluorescent molecules or fluorescence-labeled antibodies, and the entirechip after the reaction with the target biomolecules is placed on thex-y fluorescent laser reader to detect fluorescence. a detection systemfor detecting the binding of receptors and carbon nano tubes or thebinding of receptors and biomolecules may be further included. Thesetypes of binding can be detected by an electrical method or resonancemethod or by using an x-y fluorescent laser reader. When the method ofdetecting an electrical signal is applied, the binding of receptors orbiomolecules is detected by reading a minor change in voltage level ofthe carbon nano tubes occurring when the receptors or biomolecules arebound to the carbon nano tubes, using an appropriate circuit. When theresonance detection method is applied, a nano plate structure designedto have a resonance frequency of a range from megaHertzs to lowgigaHertzs is irradiated with a laser diode, and the binding ofreceptors or biomolecules to the nano plate structure is opticallymeasured by detecting a reflection signal using a position detectionphotodiode. When the x-y fluorescent laser reader is used, the targetbiomolecules bound to receptors are reacted with, for example,fluorescent molecules or fluorescence-labeled antibodies, and the entirechip after the reaction with the target biomolecules is placed on thex-y fluorescent laser reader to detect fluorescence. In particular, theentire chip is scanned with a laser beam capable of exciting thefluorescence-labeled target proteins and imaged by using acharge-coupled device (CCD) capable of scanning the entire chip array.Alternatively, a confocal microscope, which increases automation anddetects data rapidly at a high resolution, can be applied to collectdata from the chip array.

Once digitized using the nano-sensors, various algorithms can be appliedto detect a pattern associated with a substance. The chemical signal isparameterized into chemical features by a feature extractor. The outputof the feature extractor is delivered to a sub-chemical structurerecognizer A structure preselector receives the prospectivesub-structures from the recognizer and consults a dictionary to generatestructure candidates. A syntax checker receives the structure candidatesand selects the best candidate as being representative of the detectedchemical. In case the chemical is a pathogen, suitable alarms can besent.

With respect to the feature extractor, a wide range of techniques can beused, including the short time energy, the zero crossing rates, thelevel crossing rates, the filter-bank spectrum, the linear predictivecoding (LPC), and the fractal method of analysis. In addition, vectorquantization may be utilized in combination with any representationtechniques. Further, one skilled in the art may use an auditorysignal-processing model in place of the spectral models to enhance thesystem's robustness to noise and reverberation.

Nano Image Sensors

In another embodiment, the various nano devices can be integrated intoimage sensors for capture image information. Common image sensorsinclude Charge Coupled Devices (CCD) and CMOS sensors. nano devices asdescribed above can be used to act as photo collection components,charge transfer devices (such as CCD registers), and signalamplification devices in the image sensors.

Taking CCD sensors as an example, CCD image sensors can exist indifferent architectures such as Linear CCD array, Bi-Linear CCD array,Area CCD Sensor Array, and frame Transfer CCD, etc. The simplestarchitecture is a linear sensor. As shown in FIG. 8, the linear CCDarray 600 consists of a line of photodiodes 601-604, each of which isrespectively adjacent to a single CCD readout register 631-634. Thecharges collected by the photo diodes 601-604 are transferred (610) toCCD registers 631-634 under the control of the transfer gate 620. Thecharges collected are read out one pixel at a time at output signal 650after the charge signals are converted to voltage signal by readoutamplifier 640.

Although CCD architectures may be different, the basic operations of aCCD sensor all begin with the conversion of photons into electrons. Whenlight is incident on the active area of the image sensor it interactswith the atoms that make up the silicon crystal. The energy transmittedby the light (photons) is used to enable an electron to excite to theconduction band and leaving a hole in the valence band. The more photonsincident on the sensor, the more electron-hole pairs that are generated.High energy photons (short wavelengths) on the other hand are absorbedmore closely to the surface of the sensor and may not reach the activepart of the detector. Hence, there will be a spectrum over which thesensor will operate, falling off at short and long wavelengths.

The number of electrons generated per photon is known as the “quantumefficiency”, or QE. The electrons can be separated from the holes in thephoto collection areas. The amount of charge collected will depend onthe light intensity, its spectrum and the integration time. By settingout a line or a 2D array of photo collection areas, it is possible tobuild up a representation of the image incident on the sensor.

In accordance with the present invention, a 1D or 2D array of imagecollection areas are patterned by the nano-elements made up ofsingle-walled nano tubes aggregating (e.g., by van der Waals forces) insubstantially parallel orientation to form a monolayer extending indirections substantially perpendicular to the orientation of theindividual nano tubes. Such monolayer arrays can be formed byconventional techniques employing “self-assembled monolayers” (SAM) orLangmiur-Blodgett films. nano tubes 1 are bound to a substrate 2 havinga reactive coating 3 (e.g., gold). Typically, SAMs are created on asubstrate which can be a metal (such as gold, mercury or ITO(indium-tin-oxide)). The molecules of interest, here the SWNT molecules,are linked (usually covalently) to the substrate through a linkermoiety. The linker moiety may be bound first to the substrate layer orfirst to single-wall nano tubes (“SWNT”) molecule (at an open or closedend) to provide for reactive self-assembly. Langmiur-Blodgett films areformed at the interface between two phases, e.g., a hydrocarbon (e.g.,benzene or toluene) and water. Orientation in the film is achieved byemploying molecules or linkers that have hydrophilic and lipophilicmoieties at opposite ends.

The 1D or 2D array of image collection areas can include photo diodesformed by PN-type junctions discussed in US Application Serial No.20030200521, the content of which is incorporated herein by reference.The 1D or 2D nano sensor array can include arrays of crossed nanoscalewires having selectively programmable crosspoints. Nanoscale wires ofone array are shared by other arrays, providing signal propagationbetween the arrays.

The nano elements can be patterned to form a 2D array for capturing animage-wise energy pattern from photons or energy particles. Each patternnano element forms a photo diode with band gap sensitive to the photonenergies the image sensor is designed to capture. At regular intervalsphoto induced charges at each pixel must be emptied and the amount ofcharge measured to determine the local light intensity. This isaccomplished using a CCD register. A measuring device sits at the end ofthe row, known as the output node.

In another embodiment, the 1D or 2D array of image collection areas caninclude nano wires which are capable of capture photons and convert theminto photoelectrons. The orientation of the nano wires can be controlledto maximize the photon detection efficiency. Methods of aligningnanowires are discussed in US Patent Publication 20030186522, thedisclosure of which is incorporated hereof by reference.

In accordance with the present invention, the CCD registers and chargereadout circuit, the readout amplifiers (for example, 620, 631-634, 640,650) are fabricated in one or more layers made of semiconductormaterials such as silicon and silicon oxide using conventionalsemiconductor micro-fabrication technologies. The image sensitive imagelayer (comprising photo diodes 601-604) patterned with nano materials isformed over the layers of the semiconductor materials.

The charges in an image collection area, or a pixel, is transferred intoa measuring device in the semiconductor layer to produce a signal thatdepends on the amount of stored charge. The charge transfer iscontrolled by the transfer gate 620 at a predetermined clock rate. Theempty image collection area in the nano layer is ready for capturing thenext image. The downward charge transfer from the nano photo sensitivelayer to the semiconductor charge measuring layer is similar to theframe transfer CCD architecture. Detailed operations of photo inducedcharge transfers and readout are discussed in U.S. Pat. Nos. 5,946,034and 6,576,938, the disclosures of which are incorporated hereof byreference.

The nano-semiconductor CCD device as described above has the followingadvantages. Since the photon sensing pixels occupy the nano photosensitive layer on top, no photon receiving area needs to be wasted forbuilding CCD registers and voltage conversion devices. The effectivespatial fraction of image sensing can be maximized to 80-95% range.Another advantage of the nano-semiconductor CCD device in the presentinvention is the frame fresh rate is significantly increased becausephoto induced charges are transfer directly to the CCD registers, ratherthan cascade transferred between photo charge collection areas. Theseadvantages are critical for fabricating miniature and high speed imagingdevices such as digital cameras, digital video cameras, night visiondevices, telescope cameras, and microscopic cameras for scientificobservations.

In accordance to another embodiment of the present invention, thenano-semiconductor imaging device can be sensitive to different photospectrum such red, green, blue, infrared, UV etc. by using color filterarrays (CFA) disposed over the nano photo sensitive layer. Different CFApatterns include Bayer pattern, interlaced liner pattern etc. Thesemiconductor layer can further include electronic circuit forconstructing color planes from the photo-induced charges filtered byCFA. The electronic circuit can also perform various image processingoperations well known in the art. Detailed operations of CFA patternsand improvement are discussed in U.S. Pat. No. 6,366,318, thedisclosures of which are incorporated hereof by reference.

In another embodiment, nano-elements are fabricated above a CMOS imagesensor where each pixel contains three transistors: a select transistor,a source follower transistor and a reset transistor. The source followertransistor is connected to a photodiode with a nano-element formed abovethe photodiode. Light is collected by the photodiode/nano-element causesa change in the potential on the photodiode which is read out throughthe action of the select and source follower transistors. The resettransistor is used to establish a constant potential on the photodiodesprior to the start of exposure to light. In one embodiment, thenano-element is an FSA assembled geometric structure with a specificoptical absorption spectrum, a specific optical transmission spectrum, aspecific optical reflection characteristic, or a capability formodifying the polarization of light. In another embodiment, fullerenenano tubes such as an (m,n) tube can be used in conjunction with othermaterials can be used to form a Schottky barrier which would act as alight harvesting sensor or antenna. In one embodiment, a (10, 10) tubecan be connected via sulfur linkages to gold at one end of the tube andlithium at the other end of the tube forming a natural Schottky barrier.Current is generated through photo conductivity. As the (10, 10) tubeacts like an antenna, it pumps electrons into one electrode, but backflow of electrons is prevented by the intrinsic rectifying diode natureof the nano tube/metal contact. In forming an antenna, the length of thenano tube can be varied to achieve any desired resultant electricallength. The length of the molecule is chosen so that the current flowingwithin the molecule interacts with an electromagnetic field within thevicinity of the molecule, transferring energy from that electromagneticfield to electrical current in the molecule to energy in theelectromagnetic field. This electrical length can be chosen to maximizethe current induced in the antenna circuit for any desired frequencyrange. Or, the electrical length of antenna element can be chosen tomaximize the voltage in the antenna circuit for a desired frequencyrange. Additionally, a compromise between maximum current and maximumvoltage can be designed. More on the fullerene light sensor is disclosedin Application Serial No. 20020150524, the content of which isincorporated by reference.

The nano image sensor is eventually connected to various other imagingdevices such as a stand-alone digital camera (both still and videocameras), and embedded digital cameras (that may be used in cellularphones, personal digital assistants (PDA) and the like). In anotherexample implementation, various imaging devices may be coupled to imagesensor package, including digital still cameras, tethered PC cameras,imaging enabled mobile devices (e.g. cell phones, pagers, PDA's andlaptop computers), surveillance cameras, toys, machine vision systems,medical devices and image sensors for automotive applications.

In yet another embodiment, an array of electrically conductive carbonnano tube (CNT) towers are grown directly on the surface of a siliconchip. The CNT towers allow signals captured from a charge-coupled device(CCD) to be transmitted directly to the neural elements of the retina torestore vision. A retinal electrode array with a remote return electrodeis provided outside of the eye. An array of stimulating nano-electrodesis placed on the retinal surface (epiretinally) or under the retina(subretinally) and a relatively large return electrode is placed outsideof the sclera and distant from the array of stimulating electrodes. Theremote return electrode promotes deeper stimulation of retinal tissue tosupport vision.

The structures discussed above to recognize chemical substances can beapplied to recognize images as well. Such structures include HMMs,neural networks, fuzzy logic, and statistical recognizers, among others.

Nano Displays

Turning now to a different embodiment to display images, thenano-elements can be light-emitting nano particles. The production of arobust, chemically stable, crystalline, passivated nano particle andcomposition containing the same, that emit light with high efficienciesand size-tunable and excitation energy tunable color is discussed inApplication Serial No. 20030003300, the content of which is herebyincorporated b reference. The methods include the thermal degradation ofa precursor molecule in the presence of a capping agent at hightemperature and elevated pressure. A particular composition prepared bythe methods is a passivated silicon nano particle composition displayingdiscrete optical transitions. Group IV metals form nano crystalline oramorphous particles by the thermal degradation of a precursor moleculein the presence of molecules that bind to the particle surface, referredto as a capping agent at high temperature and elevated pressure. Incertain embodiments, the reaction may run under an inert atmosphere. Incertain embodiments the reaction may be run at ambient pressures. Theparticles may be robust, chemically stable, crystalline, or amorphousand organic-monolayer passivated, or chemically coated by a mixture oforganic molecules. In one embodiment, the particles emit light in theultraviolet wavelengths. In another embodiment, the particles emit lightin the visible wavelengths. In other embodiments, the particles emitlight in the near-infrared and the infrared wavelengths. The particlesmay emit light with high efficiencies. Color of the light emitted by theparticles may be size-tunable and excitation energy tunable. The lightemission may be tuned by particle size, with smaller particles emittinghigher energy than larger particles. The surface chemistry may also bemodified to tune the optical properties of the particles. In oneembodiment, the surfaces may be well-passivated for light emission athigher energies than particles with surfaces that are notwell-passivated. The average diameter of the particles may be between 1and 10 nm. A particular composition prepared by the methods is apassivated silicon nano particle composition displaying discrete opticaltransitions and photoluminescence.

In another embodiment, a light may be formed having a broad sizedistribution of silicon nano particles. The broad size distribution maybe advantageous in that the combination of wavelengths emitted by thedifferent size particles may produce a white light. The silicon nanoparticles may be embedded in a polymer matrix. The polymer matrix isnot, however, necessary for the silicon nano particles to functioneffectively as the emissive layer. The size distribution of silicon nanoparticles may allow the emission of white light. The nano particlesthemselves may emit with size-independent quantum yields and lifetimes.Clusters of nano particles may produce a broad emission band. If energytransfer occurs between neighboring nano particles, it does not resultin the selective emission from only the largest particles with thelowest energy gap between the highest occupied and lowest unoccupiedmolecular orbits (HOMO and LUMO). This situation is qualitativelydifferent than known technology using CdSe nano particles.

An embodiment of a basic design for light emitting device includes afirst electrode, second electrode, and emissive layer. Emissive layermay include the nano particles exhibiting discrete optical properties asdescribed herein. Emissive layer may include a polymer wherein the nanoparticles may be suspended. However, nano particle based light emittingdevices may not require a polymer to emit, in contrast to many organicLEDs. Polymers may inflict losses through absorption, scattering, andpoor electron-hole interfaces. Emissive layer may be positioned adjacentfirst electrode. First electrode may function as a cathode. Emissivelayer may be positioned adjacent second electrode. Second electrode mayfunction as an anode. Substrate may include a transparent conductiveoxide layer. Non-limiting examples of the transparent conductive oxidelayer may include indium tin oxide, tin oxide, or a translucent thinlayer of Ni or Au or an alloy of Ni and Au. The basic design of lightemitting devices is described in further detail in U.S. Pat. No.5,977,565 which is incorporated herein by reference. The nano particlesmay emit light by optical stimulation. In this device, an opticalexcitation source is used in place of electrical stimulation. However,in another embodiment, a combination of optical excitation andelectrical stimulation may be used to enhance device performance, suchas overall energy efficiency or perhaps color tenability.

The nano display device in the present invention can include an array oflight-emitting cells disposed in rows and columns and constructed over asubstrate. Each light emitting cell comprises a first electrode, asecond electrode, and a light-emitting nano material disposed in theintersecting region between the first electrode and the secondelectrode. The light-emitting nano material is capable of emitting lightwhen a voltage is applied between the first electrode and the secondelectrode. The nano display device of claim 1, wherein thelight-emitting nano material includes low molecular weight or polymericorganic molecules, and nano particles formed by semiconductor materialsas described below. The light-emitting nano material can emit photons atone or more wavelengths for example in the Ultra Violet, visible, andinfrared spectra. A light emitting diode is formed in eachlight-emitting cell by the light-emitting nano material, the firstelectrode, and the second electrode. A nano diode can be fabricatedusing techniques above. The light-emitting cells are insulated byinsulation regions so that each light-emitting cell can be individuallyaddressed for light emission.

In another embodiment, a molecule is used as light emitter with twoelectrodes at a tunneling distance from each other. Such a tunnelingdistance may as well lie in the subnanometer range as above that rangeand is the distance which allows a tunneling current to flow between theelectrodes. As discussed in US Application Serial 20020096633, thecontent of which is incorporated by reference, the molecule can have atertiary-butyl substituted tetracycline with the tetracycline as thecentral entity and the tertiary butyls as the peripheral entities whichare movable with respect to the central entity. The molecule has severalstable or metastable conformations depending on the states of itsentities. These states are determined by the inner binding forces of themolecule, i.e. between the peripheral entities and the central entity,and the binding forces between the entities and the environment. Themolecule is situated preferably on a crystalline substrate which servesas one of the electrodes. Hence, the inner forces of the molecule andthe forces towards the substrate determine the conformations. In a firstconformation the peripheral entities have a binding force towards tilesubstrate which dominates over the force between the central entity andthe substrate. With other words, the central entity is so far away fromthe substrate that the force between it and the substrate is weaker thanthe force between the substrate and the peripheral entities. The bindingforce between the peripheral entities and the substrate are howeversufficiently weak that the molecule is not fixed in its horizontalposition. It therefore floats around on the substrate surface at roomtemperature. Another conformation is dominated by the force between thecentral entity and the substrate. The central entity is then near enoughat the substrate that the binding force holds the central entity to thesubstrate. In this conformation, the molecule remains in its position,therefore it is also called the pinned conformation. The peripheralentities in this conformation are somehow distorted or bent or moregenerally moved from their equilibration position, i.e. the positionwhich they had in the first conformation. The holding force between thecentral entity and the substrate is stronger than eventual restoringforces between the peripheral entities and the central entity which tryto form the molecule back to the first conformation. The molecule isimmobilized by the combined force between the substrate and the centralentity and between the peripheral entities and the substrate. Themolecule can be switched between the two stable conformations. Theswitching is induced by electrical voltage but can also occur throughmechanical energy. The switching is reversible. However, alsoirreversible switching is possible for selected molecule types. When anelectrical current is allowed to flow through the substrate, lightemission occurs. The substrate may have a predetermined surfacestructure, namely for a crystalline substrate the crystalline plane inwhich it lies. Light emission occurs on various planes, such as the{111} and the {100} plane. Copper, gold or silver are exemplarysubstrate materials on which the effect can be seen. Other materials forthe substrate, such as polycrystalline materials or amorphous materialswork as well.

In another embodiment, the light emitter nano-elements can be inorganicnanocrystals. The crystal composition includes a solvent withsemiconductor nanoparticles in the solvent, wherein the solvent and thesemiconductor nanoparticles are in an effective amount in the liquidcrystal composition to form a liquid crystalline phase. Thesemiconductor nanoparticles can be rod-shaped or disk-shaped, and has anaspect ratio greater than about 2:1 or less than about 1:2. As discussedin Application Serial No. 20030136943, the content of which isincorporated by reference, the nanocrystals are treated as aconventional polymer or biological macromolecule from the assembly pointof view. This enables a wide range of chemical macromolecular assemblytechniques to be extended to inorganic solids, which possess a diverserange of optical, electrical, and magnetic properties. The opticalproperties of the semiconductor nanoparticles can depend upon theirdiameters and lengths. The photoluminescence wavelengths produced by thesemiconductor nanoparticles can be tuned over the visible range byvariation of the particle size, and the degree of polarization can becontrolled by variation of the aspect ratio. Accordingly, by tuning thesize of the semiconductor nano particles, the liquid crystalcompositions may emit different colors (i.e., different wavelengths oflight). For instance, when the semiconductor nano particles in theliquid crystal composition are about 3 nanometers wide and are about 5nanometers long, the liquid crystal composition can produce green light.When the semiconductor nano particles in the liquid crystal compositionare about 3 nanometers wide and are about 60 nanometers long, the liquidcrystal composition can produce orange light. When the semiconductornano particles in the liquid crystal composition are about 4 nanometerswide and about 6 nanometers long, the liquid crystal composition canproduce red light. Accordingly, in embodiments of the invention, theoptical properties of the liquid crystal composition can be “tuned” byadjusting the size of the nano particles in the liquid crystalcomposition. Also, because the semiconductor nano particles are alignedin embodiments of the invention, any light that is produced by thealigned semiconductor nano particles can be polarized. The semiconductornano particles may comprise any suitable semiconductor material. Forexample, suitable semiconductors include compound semiconductors.Suitable compound semiconductors include Group II-VI semiconductingcompounds such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe,BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe.Other suitable compound semiconductors include Group III-Vsemiconductors such as GaAs, GaP, GaAs—P, GaSb, InAs, InP, InSb, AlAs,AlP, and AlSb. The use of Group IV semiconductors such as germanium orsilicon may also be feasible under certain conditions.

In another embodiment, a nano-light emitting faceplate patterned withcolored-light-emitting nano pixels having a predetermined size, patternand spacing, the nano-light color emitters eliminates the need forpolarizers and color filters in the Liquid Crystal Displays, whichincreases the efficiency of light transmission, and increase brightnessand contrast, and reduces power consumption. The pattern of nano pixelsin patterns for emitting different color light can be achieved asequence spin coating steps. For example, a layer of green-photonemitting nano materials is first spin coated over nano binding areasthat is in a 2D pattern as described above. The excess green emittingnano material is removed. A second pattern of nano binding materials isformed on the substrate over the areas that is not covered by thegreen-photon emitting nano materials. The nano binding materials at thisstep may be specific to a blue-photon emitting material that issubsequently spin coated. The excess blue-photon emitting material isremoved. A red-photon emitting material is coated finally in similarsteps to complete the color emitting pattern for a full color display.

In another embodiment, electronic display can be achieved by modulatingreflective index or the orientations of the reflective axes of thenano-elements on light reflective or refractive surfaces. The modulationof the reflective index of the nano materials can be driven by a twodimensional array of electrode pairs and driver circuits as in theconventional electronic display system. Each pair of electrodes and theassociated nano material define an image pixel. The reflective index ofthe nano materials can be spatially modulated by selectively switchingon and off of the electrode pairs at different pixel locations,therefore defining an image-wise pattern. An projective electronic nanodisplay is obtained by illuminating an uniform light beam across thenano reflective (or refractive) surfaces. In summary, the nano displaydevice incldues an array of light-emitting cells disposed in rows andcolumns and constructed over a substrate. Each light emitting cellcomprises a first electrode, a second electrode, and a light-reflectiveor light-refractive nano material disposed in the intersecting regionbetween the first electrode and the second electrode. Thelight-reflective or light-refractive nano material is capable ofdeflecting light when a voltage is applied between the first electrodeand the second electrode.

The nano display devices can include driver circuits for driving rowsand columns electrodes, digital signal processing units, memory, displaymode control, power drivers which are typically found in conventionalelectronic displays. The nano display devices can include drivercircuits for driving rows and columns electrodes, digital signalprocessing units, memory, display mode control, power drivers which aretypically found in conventional electronic displays. The displaycomponent is mounted on an interconnect substrate, usually flex, andelectrical connections are made from the edge of the CMOS back plane tothe substrate. Finally, the display component is suitably encapsulated,thus providing environmental protection. Plastic encapsulation istypically used in consumer products. The resulting display modulesproduced in this manner are compact, lightweight, and relativelyinexpensive.

The magnification of the image can be accomplished using refractive orreflective lens assemblies that are well known and widely utilized instandard optical projection systems.

Nano Solar Cells

The nano-elements can be used as a solar cell as well. FIG. 9 depicts aflexible photovoltaic cell 600, in accordance with the invention, thatincludes a photosensitized interconnected nanoparticle material 603 anda charge carrier material 606 disposed between a first flexible,significantly light transmitting substrate 609 and a second flexible,significantly light transmitting substrate 612. In one embodiment, theflexible photovoltaic cell further includes a catalytic media layer 615disposed between the first substrate 609 and second substrate 612.Preferably, the photovoltaic cell 600 also includes an electricalconductor 618 deposited on one or both of the substrates 609 and 612.The methods of nano particle interconnection provided herein enableconstruction of the flexible photovoltaic cell 600 at temperatures andheating times compatible with such substrates 609 and 612. The flexible,significantly light transmitting substrates 609 and 612 of thephotovoltaic cell 600 preferably include polymeric materials.

Suitable substrate materials include, but are not limited to, PET,polyimide, PEN, polymeric hydrocarbons, cellulosics, or combinationsthereof. Further, the substrates 609 and 612 may include materials thatfacilitate the fabrication of photovoltaic cells by a continuousmanufacturing process such as, for example, a roll-to-roll or webprocess as discussed in US Application Serial No. 20030189402, thecontent of which is incorporated by reference. The substrate 609 and 612may be colored or colorless. Preferably, the substrates 609 and 612 areclear and transparent. The substrates 609 and 612 may have one or moresubstantially planar surfaces or may be substantially non-planar. Forexample, a non-planar substrate may have a curved or stepped surface(e.g., to form a Fresnel lens) or be otherwise patterned.

An electrical conductor 618 is deposited on one or both of thesubstrates 609 and 612. Preferably, the electrical conductor 618 is asignificantly light transmitting material such as, for example, ITO, afluorine-doped tin oxide, tin oxide, zinc oxide, or the like. In oneillustrative embodiment, the electrical conductor 618 is deposited as alayer between about 100 nm and about 500 nm thick. In anotherillustrative embodiment, the electrical conductor 618 is between about150 nm and about 300 nm thick. According to a further feature of theillustrative embodiment, a wire or lead line may be connected to theelectrical conductor 618 to electrically connect the photovoltaic cell600 to an external load.

As noted in Application Serial No. 20030189402, metal oxidenanoparticles are interconnected by contacting the nanoparticles with asuitable polylinker dispersed in a suitable solvent at or below roomtemperature or at elevated temperatures below about 300° C. Thenanoparticles may be contacted with a polylinker solution in many ways.For example, a nanoparticle film may be formed on a substrate and thendipped into a polylinker solution. A nanoparticle film may be formed ona substrate and the polylinker solution sprayed on the film. Thepolylinker and nanoparticles may be dispersed together in a solution andthe solution deposited on a substrate. To prepare nanoparticledispersions, techniques such as, for example, microfluidizing,attritting, and ball milling may be used. Further, a polylinker solutionmay be deposited on a substrate and a nanoparticle film deposited on thepolylinker. The photosensitized interconnected nanoparticle material 603may include one or more types of metal oxide nanotubes, as described indetail above. Preferably, the nanotubes contain titanium dioxideparticles having an average particle size of about 20 nm. A wide varietyof photosensitizing agents may be applied to and/or associated with thenanotubes to produce the photosensitized interconnected nanotubematerial 603. The photosensitizing agent facilitates conversion ofincident visible light into electricity to produce the desiredphotovoltaic effect. It is believed that the photosensitizing agentabsorbs incident light resulting in the excitation of electrons in thephotosensitizing agent. The energy of the excited electrons is thentransferred from the excitation levels of the photosensitizing agentinto a conduction band of the interconnected nanotubes 603. Thiselectron transfer results in an effective separation of charge and thedesired photovoltaic effect. Accordingly, the electrons in theconduction band of the interconnected nanotubes are made available todrive an external load electrically connected to the photovoltaic cell.In one illustrative embodiment, the photosensitizing agent is sorbed(e.g., chemisorbed and/or physisorbed) on the interconnected nanotubes603. The photosensitizing agent may be sorbed on the surfaces of theinterconnected nanotubes 603, throughout the interconnected nanotubes603, or both. The photosensitizing agent is selected, for example, basedon its ability to absorb photons in a wavelength range of operation, itsability to produce free electrons (or electron holes) in a conductionband of the interconnected nanotubes 603, and its effectiveness incomplexing with or sorbing to the interconnected nanotubes 603. Thecharge carrier material 606 portion of the photovoltaic cells may form alayer in the photovoltaic cell, be interspersed with the material thatforms the photosensitized interconnected nanotube material 603, or be acombination of both. The charge carrier material 606 may be any materialthat facilitates the transfer of electrical charge from a groundpotential or a current source to the interconnected nanotubes 603(and/or a photosensitizing agent associated therewith). A general classof suitable charge carrier materials can include, but are not limited tosolvent based liquid electrolytes, polyelectrolytes, polymericelectrolytes, solid electrolytes, n-type and p-type transportingmaterials (e.g., conducting polymers), and gel electrolytes.

In another embodiment, nanocrystalline TiO₂ is replaced by a monolayermolecular array of short carbon nanotube molecules. The photoactive dyeneed not be employed since the light energy striking the tubes will beconverted into an oscillating electronic current which travels along thetube length. The ability to provide a large charge separation (thelength of the tubes in the array) creates a highly efficient cell. Aphotoactive dye (such as cis-[bisthiacyanatobis(4,4′-dicarboxy-2,2′-bipyridine Ru (II))] can be attached to the endof each nanotube in the array to further enhance the efficiency of thecell. In another embodiment of the present invention, the TiO₂nanostructure described by Grtzel in U.S. Pat. No. 5,084,365(incorporated herein by reference in its entirety) can serve as anunderlying support for assembling an array of SWNT molecules. In thisembodiment, SWNTs are attached directly to the TiO₂ (by absorptiveforces) or first derivatized to provide a linking moiety and then boundto the TiO.sub.2 surface. This structure can be used with or without aphotoactive dye as described above.

In yet another embodiment, instead of nanotubes, shape-controlledinorganic nanocrystals can be used. Shape-controlled inorganicnanocrystals offer controlled synthesis that allows not only theprediction of a structure based on computer models, but also theprediction of a precise synthetic recipe that produces that exactstructure in high-purity and high-yield, with every particle identicalto every other particle. Inorganic semiconductor nanocrystals cancontrol variables such as length, diameter, crystallinity, dopingdensity, heterojunction formation and most importantly composition.Inorganic semiconductor nanocrystals can be fabricated from all of theindustrially important semiconductor materials, including all of theGroup III-V, Group II-VI and Group IV materials and their alloys, aswell as the transition metal oxides. Furthermore, the inorganicsemiconductor nanostructures can be fabricated such that materialcharacteristics change controllably throughout the nanostructure toengineer additional functionality (i.e. heterostructures) and complexityinto the nanostructure. As discussed in US Application Serial No.20030145779, three dimensional tetrapods may be important alternativesto nanocrystal fibers and rods as additives for mechanical reinforcementof polymers (e.g., polymeric binders including polyethylene,polypropylene, epoxy functional resins, etc.). Tetrapod shapednanocrystal particles, for example, can interlock with each other andcan serve as a better reinforcing filler in a composite material (e.g.,with a binder), than for example, nanospheres. The nanocrystal particlescan be mixed with the binder using any suitable mixing apparatus. Afterthe composite material is formed, the composite material can be coatedon a substrate, shaped, or further processed in any suitable manner.

An exemplary photovoltaic device may have nanocrystal particles in abinder. This combination can then be sandwiched between two electrodes(e.g., an aluminum electrode and an indium tin oxide electrode) on asubstrate to form a photovoltaic device. Two separate mixtures can beused: one containing inorganic semiconductors made of cadmium selenide(CdSe) nanorod molecules and one containing the organic polymer to beblended with the nanorods. The mixtures are then combined and spin-castat room temperature to produce an even film of nanorods that'sapproximately 200 nanometers thick—about a thousandth the thickness of ahuman hair. Tetrapods also have independent tunability of the arm lengthand the band gap, which is attractive for nanocrystal based solar cellsor other types of photovoltaic devices. In comparison to nanocrystalparticles that are randomly oriented, the tetrapods are aligned and canprovide for a more unidirectional current path than randomly orientednanocrystal particles.

In one embodiment, each flexible photovoltaic cell further includes oneor more flexible light-transmitting substrates, a photosensitizedinterconnected nanoparticle material, and an electrolyte redox system.In general, the nanotube material and the electrolyte redox system areboth disposed between the first and second substrates. The flexible basemay be the first significantly light-transmitting substrate of theflexible photovoltaic cell. In one embodiment, the flexible photovoltaiccell further includes a photosensitized nanomatrix layer and a chargecarrier medium. The photovoltaic cell may energize the display elementdirectly, or may instead charge a power source in electricalcommunication with the display element. The display apparatus mayfurther include an addressable processor and/or computer interface,operably connected to the at least one photovoltaic cell, forcontrolling (or facilitating control of) the display element.

“Semiconductor-nanocrystal” includes semiconducting crystallineparticles of all shapes and sizes. They can have at least one dimensionless than about 100 nanometers, but they are not so limited. Rods may beof any length. “Nanocrystal”, “nanorod” and “nanoparticle” can and areused interchangeably herein. In some embodiments of the invention, thenanocrystal particles may have two or more dimensions that are less thanabout 100 nanometers. The nanocrystals may be core/shell type or coretype. For example, some branched nanocrystal particles according to someembodiments of the invention can have arms that have aspect ratiosgreater than about 1. In other embodiments, the arms can have aspectratios greater than about 5, and in some cases, greater than about 10,etc. The widths of the arms may be less than about 200, 100, and even 50nanometers in some embodiments. For instance, in an exemplary tetrapodwith a core and four arms, the core can have a diameter from about 3 toabout 4 nanometers, and each arm can have a length of from about 4 toabout 50, 100, 200, 500, and even greater than about 1000 nanometers. Ofcourse, the tetrapods and other nanocrystal particles described hereincan have other suitable dimensions. In embodiments of the invention, thenanocrystal particles may be single crystalline or polycrystalline innature.

IC Packaging

The foregoing electronic devices are generally housed in a packageincluding a chip with a plurality of chip pads formed on the chip asinput/output ports for a variety of signals. A lead frame includes aplurality of contact points which are electrically connected to the chippads to receive the variety of signals from or to output the same to anexternal circuit. Further, bonding wires electrically connect each chippad to its respective contact points on the lead frame. The bondingwires comprise one or more of nano material such as Fullerene molecules,nanotubes, nanowires, nanocomposite material, nanostructured carbonmaterial as described below.

The structure of the package is protected by, for example, anano-ceramic power compound or resin as described below to remove heat.

Fullerene molecular wires are used to replace conventional bondingwires. In one embodiment, the bonding wires can be FSAs or self-assemblyassisted by binding to FSA or fullerene nano-wires. Choice of FSAs canalso enable self-assembly of compositions whose geometry imparts usefulchemical or electrochemical properties including operation as a catalystfor chemical or electrochemical reactions, sorption of specificchemicals, or resistance to attack by specific chemicals, energy storageor resistance to corrosion. Examples of biological properties of FSAself-assembled geometric compositions include operation as a catalystfor biochemical reactions; sorption or reaction site specific biologicalchemicals, agents or structures; service as a pharmaceutical ortherapeutic substance; interaction with living tissue or lack ofinteraction with living tissue; or as an agent for enabling any form ofgrowth of biological systems as an agent for interaction withelectrical, chemical, physical or optical functions of any knownbiological systems.

FSA assembled geometric structures can also have useful mechanicalproperties which include but are not limited to a high elastic tomodulus weight ratio or a specific elastic stress tensor. Self-assembledstructures, or fullerene molecules, alone or in cooperation with oneanother (the collective set of alternatives will be referred to as“molecule/structure”) can be used to create devices with usefulproperties. For example, the molecule/structure can be attached byphysical, chemical, electrostatic, or magnetic means to anotherstructure causing a communication of information by physical, chemical,electrical, optical or biological means between the molecule/structureand other structure to which the molecule/structure is attached orbetween entities in the vicinity of the molecule/structure. Examplesinclude, but are not limited to, physical communication via magneticinteraction, chemical communication via action of electrolytes ortransmission of chemical agents through a solution, electricalcommunication via transfer of electronic charge, optical communicationvia interaction with and passage of any form with biological agentsbetween the molecule/structure and another entity with which thoseagents interact.

The bonding wires can also act as antennas. For example, the lengths,location, and orientation of the molecules can be determined by FSAs sothat an electromagnetic field in the vicinity of the molecules induceselectrical currents with some known phase relationship within two ormore molecules. The spatial, angular and frequency distribution of theelectromagnetic field determines the response of the currents within themolecules. The currents induced within the molecules bear a phaserelationship determined by the geometry of the array. In addition,application of the FSAs could be used to facilitate interaction betweenindividual tubes or groups of tubes and other entities, whichinteraction provides any form of communication of stress, strain,electrical signals, electrical currents, or electromagnetic interaction.This interaction provides an “interface” between the self-assembled nanostructure and other known useful devices. In forming an antenna, thelength of the nano tube can be varied to achieve any desired resultantelectrical length. The length of the molecule is chosen so that thecurrent flowing within the molecule interacts with an electromagneticfield within the vicinity of the molecule, transferring energy from thatelectromagnetic field to electrical current in the molecule to energy inthe electromagnetic field. This electrical length can be chosen tomaximize the current induced in the antenna circuit for any desiredfrequency range. Or, the electrical length of an antenna element can bechosen to maximize the voltage in the antenna circuit for a desiredfrequency range. Additionally, a compromise between maximum current andmaximum voltage can be designed. A Fullerene nano tube antenna can alsoserve as the load for a circuit. The current to the antenna can bevaried to produce desired electric and magnetic fields. The length ofthe nano tube can be varied to provide desired propagationcharacteristics. Also, the diameter of the antenna elements can bevaried by combining an optimum number of strands of nano tubes. Further,these individual nano tube antenna elements can be combined to form anantenna array. The lengths, location, and orientation of the moleculesare chosen so that electrical currents within two or more of themolecules act coherently with some known phase relationship, producingor altering an electromagnetic field in the vicinity of the molecules.This coherent interaction of the currents within the molecules acts todefine, alter, control, or select the spatial, angular and frequencydistributions of the electromagnetic field intensity produced by theaction of these currents flowing in the molecules. In anotherembodiment, the currents induced within the molecules bear a phaserelationship determined by the geometry of the array, and these currentsthemselves produce a secondary electromagnetic field, which is radiatedfrom the array, having a spatial, angular and frequency distributionthat is determined by the geometry of the array and its elements. Onemethod of forming antenna arrays is the self-assembly monolayertechniques discussed above.

Various molecules or nano-elements can be coupled to one or moreelectrodes in a layer of an IC substrate using standard methods wellknown to those of skill in the art. The coupling can be a directattachment of the molecule to the electrode, or an indirect attachment(e.g. via a linker). The attachment can be a covalent linkage, an ioniclinkage, a linkage driven by hydrogen bonding or can involve no actualchemical attachment, but simply a juxtaposition of the electrode to themolecule. In some preferred embodiments, a “linker” is used to attachthe molecule(s) to the electrode. The linker can be electricallyconductive or it can be short enough that electrons can pass directly orindirectly between the electrode and a molecule of the storage medium.The manner of linking a wide variety of compounds to various surfaces iswell known and is amply illustrated in the literature. Means of couplingthe molecules will be recognized by those of skill in the art. Thelinkage of the storage medium to a surface can be covalent, or by ionicor other non-covalent interactions. The surface and/or the molecule(s)may be specifically derivatized to provide convenient linking groups(e.g. sulfur, hydroxyl, amino, etc.). In one embodiment, the moleculesor nano-elements self-assemble on the desired electrode. Thus, forexample, where the working electrode is gold, molecules bearing thiolgroups or bearing linkers having thiol groups will self-assemble on thegold surface. Where there is more than one gold electrode, the moleculescan be drawn to the desired surface by placing an appropriate (e.g.attractive) charge on the electrode to which they are to be attachedand/or placing a “repellant” charge on the electrode that is not to beso coupled.

The FSA bonding wires can be used alone or in conjunction with otherelements. A first group of elements includes palladium (Pd), rhodium(Rh), platinum (Pt), and iridium (Ir). As noted in US Patent ApplicationSerial No. 20030209810, in certain situations, the chip pad is formed ofaluminum (Al). Accordingly, when a gold-silver (Au—Ag) alloy bondingwire is attached to the chip pad, the Au of the bonding wire diffusesinto the chip pad, thereby resulting in a void near the neck. Thenano-bonding wire, singly or in combination with the elements of thefirst group form a barrier layer in the interface between a Au-richregion (bonding wire region) and an Al-rich region (chip pad region)after wire bonding, to prevent diffusion of Au and Ag atoms, therebysuppressing intermetallic compound and Kirkendall void formation. As aresult, a reduction in thermal reliability is prevented.

Nano-bonding wires can also be used singly or in combination with asecond group of elements that includes boron (B), beryllium (Be), andcalcium (Ca). The elements of the second group enhances tensile strengthat room temperature and high temperature and suppresses bending ordeformation of loops, such as sagging or sweeping, after loop formation.When an ultra low loop is formed, the elements of the second groupincrease yield strength near the ball neck, and thus reduce or prevent arupture of the ball neck. Especially, when the bonding wire has a smalldiameter, a brittle failure near the ball neck can be suppressed.

Nano-bonding wires can also be used singly or in combination with athird group of elements that includes phosphorous (P), antimony (Sb),and bismuth (Bi). The elements of the third group are uniformlydispersed in a Au solid solution to generate a stress field in the goldlattice and thus to enhance the strength of the gold at roomtemperature. The elements of the third group enhance the tensilestrength of the bonding wire and effectively stabilize loop shape andreduce a loop height deviation.

Nano-bonding wires can also be used singly or in combination with afourth group of elements that includes magnesium (Mg), thallium (TI),zinc (Zn), and tin (Sn). The elements of the fourth group suppress thegrain refinement in a free air ball and soften the ball, therebypreventing chip cracking, which is a problem of Au—Ag alloys, andimproving thermal reliability.

The nano-bonding wires provide superior electrical characteristics aswell as mechanical strength in wire bonding applications. In a wirebonding process, one end of the nano bonding wire is melted bydischarging to form a free air ball of a predetermined size and pressedon the chip pad to be bound to the chip pad. A loop of the nano bondingwire having an appropriate height and length is formed to reach acorresponding lead frame, and the other end of the bonding wire is boundto the lead frame with an application of pressure. As a result, the chipand the lead frame are electrically connected. For low cost production,the chip can be embedded inside a suitable epoxy. Alternatively, thechip can be embedded in a plastic flexible substrate that caninterconnect a number of other chips. For example, in a plastic flexiblecredit card, a solar cell is mounted, printed or suitably positioned ata bottom layer to capture photons and convert the photons into energy torun the credit card operation. Display and processor electronics arethen mounted or on a plastic substrate. A transceiver chip with nanoantennas is also mounted or printed on the plastic substrate.

For high performance applications that generate large amounts of heatsuch as processor chips, the resulting chip is then bonding to anano-ceramic housing to maximize heat radiation and to control chiptemperature.

As discussed in US Application Serial No 20040029706, the content ofwhich is incorporated by reference, methods are disclosed for usingceramic nanocomposites in applications requiring thermal barriermaterials and in applications requiring material properties selectedfrom the group consisting of thermally insulating, electricallyconducting, mechanically robust, and combinations thereof. However, forcertain electrical applications, thermal conductance is required.

In one embodiment of the present system, a heat conducting ceramicnanocomposite for removing unwanted heat is made with a ceramic hostmaterial and a nanostructured carbon material selected from the groupconsisting of carbon nanotubes, single-wall carbon nanotubes, vaporgrown carbon fibers, fullerenes, buckyballs, carbon fibrils,buckyonions, metallofullerenes, endohedral fullerenes, and combinationsthereof. In some embodiments, the nanostructured carbon material servesto increase the thermal conductivity of the ceramic host. In someembodiments, it does this by serving as a phonon concentrating center.In other embodiments, it increases the thermal conductivity by alteringthe structure of the ceramic host. In some embodiments of the presentsystem, at least some of the nanostructured carbon material presentimparts greater structural integrity to the ceramic host. A ceramicnanocomposite, according to the present system, can exist in the form ofcoatings, bulk objects, and combinations thereof. The ceramic host ofthe nanocomposite of the present system can be any ceramic whichsuitably provides for the nanocomposite material of the present system.Suitable ceramics include, but are not limited to, zirconia, alumina,silica, titania, yttria, ceria, boron nitride, carbon nitride, siliconnitride, silicon carbide, tantalum carbide, tungsten carbide, andcombinations thereof. In some embodiments, the nanostructured carbonmaterial comprises single-wall carbon nanotubes which may, or may not,be in the form of short “pipes.” In some embodiments, the nanostructuredcarbon material is modified by a chemical means to yield derivatizednanostructured carbon material. Here, “derivatization” is taken to meanattachment of other chemical entities to the nanostructured carbonmaterial. This attachment may be by chemical or physical meansincluding, but not limited to, covalent bonding, van der Waals forces,electrostatic forces, physical entanglement, and combinations thereof.In other embodiments, the nanostructured carbon material is modified bya physical means selected from the group consisting of plasma treatment,heat treatment, ion bombardment, attrition by impact, milling andcombinations thereof. In other embodiments, the nanostructured carbonmaterial is modified by a chemical means selected from the groupconsisting of chemical etching by acids either in liquid or gaseousform, chemical etching by bases either in liquid or gaseous form,electrochemical treatments, and combinations thereof.

In another embodiment, the chip substrate can be in contact with severalthin-film thermoelectric elements placed in parallel to heat or cool aparticular area depending on the direction of current flow in theseelements. Each thermoelectric nano-element has an n-type thermoelectricmaterial, a p-type thermoelectric material located adjacent to then-type thermoelectric material, a Peltier contact connecting the n-typethermoelectric material to the p-type thermoelectric material.Electrodes contact both a side of the n-type thermoelectric materialopposite the Peltier contact and a side of the p-type thermoelectricmaterial opposite the Peltier contact. Appropriately biased electricalcurrent flow through selected ones of the thermoelectric elements makesthe Peltier contact either a heated junction or a cooled junction. Inanother embodiment, only one leg of the thermoelectric element isrequired to produce heating or cooling. In this embodiment, a selectedtype of thermoelectric material (i.e. n-type or p-type) is utilized withthe Peltier contact. Current flow in a first direction through anelectrode, a thermoelectric material, the Peltier contact, and asubsequent electrode results in a heated junction at the Peltiercontact. A current flow in a second direction opposite to the firstproduces a cooled junction at the Peltier contact. As disclosed in USPatent Application No. 20020174660, the content of which is incorporatedby reference, a cantilever similar to arrangements known in the art foratomic force microscopy (AFM) can be used. The integration of athermoelectric cooling/heating device or module with a cantilever,especially the cantilevers similar to those used in AFM, provides for“nanometer-size temperature control” of bio-tissues, cells, and perhapsother atomic-scale structures in nano technology such as for examplenano-self-assembly.

In some embodiments of the present system, a method for making ceramicnanocomposites comprising a nanostructured carbon component and aceramic host component includes preparing a slurry comprising ceramicparticles and solvent; and adding nanostructured carbon materials suchthat they become dispersed in the slurry. The solvent used to preparethe slurry can be selected from the group consisting of aqueoussolvents, non-aqueous solvent, and combinations thereof. Such solventsinclude, but are not limited to, water, toluene, ethyl alcohol,trichloroethylene, methyl ethyl ketone, and combinations thereof. Insome embodiments, the step of preparing the slurry further comprisesadding a dispersal agent. Such dispersal agents include, but are notlimited to, natural formulations, synthetic formulations,polyelectrolyte dispersants, surfactants, wrapping polymers, andcombinations thereof. In some embodiments, the step of preparing theslurry further comprises adding binding agents and/or plasticizers.

In some embodiments of the present system, the adding the nanostructuredcarbon materials (note that this step can be combined with the step ofpreparing the slurry) to the slurry further comprises the utilization ofdispersion assistance to facilitate dispersion. In some embodiments,this step further comprises a milling operation, and possibly ananomilling operation. In some embodiments of the present system, theslurry is shaped by a casting technique. Suitable casting techniquesinclude, but are not limited to, tape casting, spin casting, solidcasting, slip casting, robocasting, and combinations thereof. In someembodiments, the step of shape-forming comprises a gel castingtechnique. Here, a “sol-gel” technique is one which provides for aceramic component first as a solution or “sol” of precursors which ishydrolyzed and polymerized into a “gel.” Thus, the term, “sol-gel”represents the material at any stage of its transformation from asolution to a gel. The method of making coatings and objects can alsoinclude spraying these ceramic nanocomposite powders with a techniqueselected from the group consisting of plasma spraying, thermal spraying,powder spraying, electrostatically-assisted powder spraying, andcombinations thereof.

In various embodiments, nano-elements can be formed in conjunction withnano-sized materials include, but are not limited to, ceramics,intermetallics, and metals. Other examples of nano-sized materialsaccording to embodiments of the present invention include coated andencapsulated materials. Ceramic materials and intermetallics are oftenused to enhance, for example, the high-temperature mechanical strengthof the nanocomposite material. In some embodiments the ceramic comprisesan oxide, such as, for example, an oxide comprising at least one ofaluminum, yttrium, zirconium, and cerium. In other embodiments, theceramic comprises at least one of a carbide, a nitride, and a boride. Instill other embodiments, the intermetallic comprises a silicide. Incertain embodiments where the nano-sized material comprises a metal, thenano-sized metal has a melting temperature higher than that of themolten material such that the nano-sized metal remains substantiallyinert with respect to the molten metal. Metals with high melting points,for example, tungsten, are suitable as nano-sized materials forembodiments of this type. It will be appreciated by those skilled in theart that the choice of any specific combination of molten material andnano-sized material is based upon the combination of properties desiredfor the resultant nanocomposite material, including, but not limited to,physical, chemical, mechanical, electrical, magnetic, and thermalproperties.

In one embodiment, an electronic device is formed with a nanocompositematerial. The method includes providing a molten material; providing anano-sized electronic device along with other nano-material, thenano-sized electronic device/material being substantially inert withrespect to the molten material; introducing the nano-sized material intothe molten material; dispersing the nano-sized material within themolten material using at least one dispersion technique selected fromthe group consisting of agitating the molten material using ultrasonicenergy to disperse the nano-sized material within the molten material;introducing at least one active element into the molten material toenhance wetting of the nano-sized material by the molten material; andcoating the nano-sized material with a wetting agent to promote wettingof the molten metal on the nano-sized material; and solidifying themolten material to form a solid nanocomposite material, thenanocomposite material comprising a dispersion of the nano-sizedmaterial within a solid matrix. Additional materials include those notedin US Application Serial No. 20040016318, the content of which isincorporated by reference. The electronic devices self-assemble insidethe matrix after the dispersion. Such a nano-composite material withbuilt-in transistors, processors, memories and other electronics formsintelligent articles such as medical prostheses, smart clothing, smartappliances and smart vehicles and smart robots, among others. Thesearticles in turn are powered by nano fuel cells as disclosed in commonlyowned patent application Ser. Nos. 11/064,363 and 11/064,366, thecontent of which is incorporated by reference.

The resulting composite material can be a nanocomposite magnet, amagnetic refrigerator element, an abrasion resistant surface coat, ahigher-order structure piezoelectric element composed of a mixture ofpiezoelectric materials different in frequency response property, aheating element, a higher-order structure dielectric displaying thecharacteristics over a wide range of temperature, a photocatalystmaterial and the induction material thereof, a functional surface coatcomposed of a mixture of materials having such properties as the waterholding property, hydrophilicity, and water repellency, a minute machinepart, an abrasion resistant coat for a magnetic head, an electrostaticchuck, a sliding member material, an abrasion resistant coat of a dieand mending the abraded and chipped parts thereof, an insulating coat ofan electrostatic motor, an artificial bone, an artificial dental root, acondenser, an electronic circuit part, an oxygen sensor, an oxygen pump,a sliding part of a valve, a distortion gauge, a pressure-sensitivesensor, a piezoelectric actuator, a piezoelectric transformer, apiezoelectric buzzer, a piezoelectric filter, an optical shutter, anautomobile knock sensor, a supersonic sensor, an infrared sensor, anantivibration plate, a cutting machining tool, a surface coat of acopying machine drum, a polycrystalline solar cell, a dye sensitizationtype solar cell, a surface coat of a kitchen knife or a knife, the ballof a ball point pen, a temperature sensor, the insulation coat of adisplay, a superconductor thin film, a Josephson element, a superplastic structure body, a ceramic heating element, a microwavedielectric, a water-repellent coat, an antireflection film, a heat rayreflecting film, a UV absorbing film, an inter-metal dielectric layer(IMD), a shallow trench isolation (STI), and the like. In variousembodiments, nano-elements such as FSAs are used as fillers in a varietyof pure phase materials such as polymers that are now readily availableat low cost. The nanofiller may be mixed with a monomer, which is thenpolymerized to form a polymer matrix composite. In another embodiment,the nanofiller may be mixed with a matrix powder composition andcompacted to form a solid composite. In yet another embodiment, thematrix composition may be dissolved in a solvent and mixed with thenanofiller, and then the solvent may be removed to form a solidcomposite. In still another embodiment, the matrix may be a liquid orhave liquid like properties. The nano-fillers improve the properties ofthe low cost pure phase materials including, for example, electricalconductivity, magnetic permeability, dielectric constant, and thermalconductivity. A matrix is blended with a filler material with desirableproperties that can include refractive index, transparency to light,reflection characteristics, resistivity, permittivity, permeability,coercivity, B-H product, magnetic hysteresis, breakdown voltage, skindepth, curie temperature, dissipation factor, work function, band gap,electromagnetic shielding effectiveness, radiation hardness, chemicalreactivity, thermal conductivity, temperature coefficient of anelectrical property, voltage coefficient of an electrical property,thermal shock resistance, biocompatibility, and/or wear rate. Thedesired material property is selected from the group consisting ofrefractive index, transparency to light, reflection characteristics,resistivity, permittivity, permeability, coercivity, B-H product,magnetic hysteresis, breakdown voltage, skin depth, curie temperature,dissipation factor, work function, band gap, electromagnetic shieldingeffectiveness, radiation hardness, chemical reactivity, thermalconductivity, temperature coefficient of an electrical property, voltagecoefficient of an electrical property, thermal shock resistance,biocompatibility and wear rate. The nanostructured filler may compriseone or more elements selected from the s, p, d, and f groups of theperiodic table, or it may comprise a compound of one or more suchelements with one or more suitable anions, such as aluminum, antimony,boron, bromine, carbon, chlorine, fluorine, germanium, hydrogen, indium,iodine, nickel, nitrogen, oxygen, phosphorus, selenium, silicon, sulfur,or tellurium. The matrix may be a polymer (e.g., poly(methylmethacrylate), poly(vinyl alcohol), polycarbonate, polyalkene, orpolyaryl), a ceramic (e.g., zinc oxide, indium-tin oxide, hafniumcarbide, or ferrite), or a metal (e.g., copper, tin, zinc, or iron).Other filler materials include those in Application Serial No.20030207978, the content of which is incorporated by reference.

Energy Source

FIG. 10 shows one embodiment of a mobile power unit 1. The unit 1 hasone or more fuel cells 30. The output of the fuel cells is directcurrent (DC) which is provided to an inverter 40 for generating ACvoltages to operate mobile equipment. Since the fuel cell 30 compactlystores large quantity of energy, the entire mobile power unit 1 isapproximately the size of a cigarette pack and yet can power ACequipment in the field for days. When the fuel cells 30 are depleted,they can be refueled in situ, thus allowing the AC equipment to operatewithout interruption.

Fuel cells enable the electrochemical conversion of fuel gases andoxygen into oxidized products and electrical energy. The difference fromtraditional chemical processes consists of performing reduction andoxidation of the components, separately, at two electrodes. Chemicalreaction of the reactants at the electrodes occurs because ionicconduction is ensured via a gas-tight electrolyte, and the transport ofelectrons takes place only via an external circuit. The hydrogen isobtained from fossil fuels. Typical representatives of these fuels arenatural gas, methanol and aliphatic or aromatic hydrocarbons, as well asmixtures thereof, such as, for example, petrol and diesel oil. Inprinciple, it is also possible to produce the hydrogen-containing fuelgas biologically and directly as synthesis gas and to work it up in anappropriate manner for use in a fuel cell. Methanol can also be producedbiologically, for example, with the aid of methylotrophic yeasts.

In one embodiment, the cell 30 stores hydrogen which has previously beenproduced from electricity and water. The cell 30 is a cost-effective andpollution-free energy storage device. Different types of fuel cellsincluding proton exchange membranes, solid oxides, high temperature fuelcells, and regenerative fuel cells can be used. In one embodiment, aproton exchange membrane (PEM) fuel cell includes an anode, a cathode,and a selective electrolytic membrane disposed between the twoelectrodes. In a catalyzed reaction, a fuel such as hydrogen is oxidizedat the anode to form cations (protons) and electrons. The ion exchangemembrane facilitates the migration of protons from the anode to thecathode. The electrons cannot pass through the membrane and are forcedto flow through an external circuit thus providing an electricalcurrent. At the cathode, oxygen reacts at the catalyst layer, withelectrons returned from the electrical circuit, to form anions. Theanions formed at the cathode react with the protons that have crossedthe membrane to form liquid water as the reaction product. Typically, acombustion reaction is not involved. Accordingly, fuel cells are cleanand efficient.

The hydrogen in the fuel cell 30 can also move through an activetransport membrane (ATM). In the ATM embodiment, the fuel cell 30employs molecules used in biological processes to create fuel cells thatoperate at moderate temperatures and without the presence of harshchemicals maintained at high temperatures, which can lead to corrosionof the cell components. The compact, inert energy sources can be used toprovide short duration electrical output. Since the materials retainedwithin the fuel cells are non-corrosive and typically not otherwisehazardous, it is practical to recharge the fuel cells with fuel, withthe recharging done by the user. Alternatively, the fuel cells 30 can beelectrically re-charged.

In one embodiment, the fuel cell includes a first compartment with anelectron carrier in communication with redox enzymes to deliverelectrons to a first electrode; a second compartment having an electronreceiving composition in chemical communication with a second electrode,and a barrier separating the first compartment from the secondcompartment; said barrier having embedded proton transporting proteinseffective to transport protons from the first compartment to the secondcompartment. During operation, an electrical current flows along aconductive pathway formed between the first electrode and the secondelectrode.

The first compartment can include an electron transfer mediator thattransfers electrons from the redox enzymes to the first electrode. Theproton transporting proteins include redox enzyme activity. A reservoircan be used for supplying to the vicinity of at least one of theelectrodes a component consumed in the operation of the fuel cell and apump for drawing such component to that vicinity.

As discussed in U.S. Pat. No. 6,500,571, the content of which isincorporated by reference, examples of particularly preferred enzymesproviding one or both of the oxidation/reduction and proton pumpingfunctions include, for example, NADH dehydrogenase (e.g., from E. coli.Tran et al., “Requirement for the proton pumping NADH dehydrogenase I ofEscherichia coli in respiration of NADH to fumarate and its bioenergeticimplications,” Eur. J. Biochem. 244: 155, 1997), NADPH transhydrogenase,proton ATPase, and cytochrome oxidase and its various forms. Methods ofisolating such an NADH dehydrogenase enzyme are described in detail, forexample, in Braun et al., Biochemistry 37: 1861-1867, 1998; and Bergsmaet al., “Purification and characterization of NADH dehydrogenase fromBacillus subtilis,” Eur. J. Biochem. 128: 151-157, 1982. The lipidbilayer can be formed across the perforations 49 and enzyme incorporatedtherein by, for example, the methods described in detail in Niki et al.,U.S. Pat. No. 4,541,908 (annealing cytochrome C to an electrode) andPersson et al., J. Electroanalytical Chem. 292: 115, 1990. Such methodscan comprise the steps of: making an appropriate solution of lipid andenzyme, where the enzyme may be supplied to the mixture in a solutionstabilized with a detergent; and, once an appropriate solution of lipidand enzyme is made, the perforated dielectric substrate is dipped intothe solution to form the enzyme-containing lipid bilayers. Sonication ordetergent dilution may be required to facilitate enzyme incorporationinto a bilayer. See, for example, Singer, Biochemical Pharmacology 31:527-534, 1982; Madden, “Current concepts in membrane proteinreconstitution,” Chem. Phys. Lipids 40: 207-222, 1986; Montal et al.,“Functional reassembly of membrane proteins in planar lipid bilayers,”Quart. Rev. Biophys. 14: 1-79, 1981; Helenius et al., “Asymmetric andsymmetric membrane reconstitution by detergent elimination,” Eur. J.Biochem. 116: 27-31, 1981; Volumes on biomembranes (e.g., Fleischer andPacker (eds.)), in Methods in Enzymology series, Academic Press.

Using enzymes having both the oxidation/reduction and proton pumpingfunctions, and which consume electron carrier, the acidification of thefuel side caused by the consumption of electron carrier is substantiallyoffset by the export of protons. Net proton pumping in conjunction withreduction of an electron carrier can exceed 2 protons per electrontransfer (e.g., up to 3 to 4 protons per electron transfer).Accordingly, in some embodiments care must be taken to buffer oraccommodate excess de-acidification on the fuel side or excessacidification of the product side. Alternatively, the rate of transportis adjusted by incorporating a mix of redox enzymes, some portion ofwhich enzymes do not exhibit coordinate proton transport. In someembodiments, care is taken especially on the fuel side to moderateproton export to match proton production. Acidification orde-acidification on one side or another of the fuel cell can also bemoderated by selecting or mixing redox enzymes to provide a desiredamount of proton production. Of course, proton export from the fuel sideis to a certain degree self-limiting, such that in some embodiments thetheoretical concern for excess pumping to the product side is of, atbest, limited consequence. For example, mitochondrial matrix proteinswhich oxidize electron carriers and transport protons operate to createa substantial pH gradient across the inner mitochondrial membrane, andare designed to operate as pumping creates a relatively high pH such aspH 8 or higher. (In some embodiments, however, care is taken to keep thepH in a range closer to pH 7.4, where many electron carriers such asNADH are more stable.) Irrespective of how perfectly proton productionis matched to proton consumption, the proton pumping provided by thisembodiment of the invention helps diminish loses in the electrontransfer rate due to a shortfall of protons on the product side. In someembodiments, proton pumping is provided by a light-driven proton pumpsuch as bacteriorhodopsin. Recombinant production of bacteriorhodopsinis described, for example, in Nassal et al., J. Biol. Chem. 262:9264-70, 1987. All trans retinal is associated with bacteriorhodopsin toprovide the light-absorbing chromophore. Light to power this type ofproton pump can be provided by electronic light sources, such as LEDs,incorporated into the fuel cell and powered by a (i) portion of energyproduced from the fuel cell, or (ii) a translucent portion of the fuelcell casing that allows light from room lighting or sunlight to impingethe lipid bilayer.

The fuel cell operates within a temperature range appropriate for theoperation of the redox enzyme. This temperature range typically varieswith the stability of the enzyme, and the source of the enzyme. Toincrease the appropriate temperature range, one can select theappropriate redox enzyme from a thermophilic organism, such as amicroorganism isolated from a volcanic vent or hot spring. Nonetheless,preferred temperatures of operation of at least the first electrode areabout 80.degree. C. or less, preferably 60.degree. C. or less, morepreferably 40.degree. C. or 30.degree. C. or less. The porous matrix is,for example, made up of inert fibers such as asbestos, sinteredmaterials such as sintered glass or beads of inert material.

The first electrode (anode) can be coated with an electron transfermediator such as an organometallic compound which functions as asubstitute electron recipient for the biological substrate of the redoxenzyme. Similarly, the lipid bilayer of the embodiment of FIG. 3 orstructures adjacent to the bilayer can incorporate such electrontransfer mediators. Such organometallic compounds can include, withoutlimitation, dicyclopentadienyliron (C.sub.10 H.sub.10 Fe, ferrocene),available along with analogs that can be substituted, from Aldrich,Milwaukee, Wis., platinum on carbon, and palladium on carbon. Furtherexamples include ferredoxin molecules of appropriate oxidation/reductionpotential, such as the ferredoxin formed of rubredoxin and otherferredoxins available from Sigma Chemical. Other electron transfermediators include organic compounds such as quinone and relatedcompounds. The electron transfer mediator can be applied, for example,by screening or masked dip coating or sublimation. The first electrodecan be impregnated with the redox enzyme, which can be applied before orafter the electron transfer mediator. One way to assure the associationof the redox enzyme with the electrode is simply to incubate a solutionof the redox enzyme with electrode for sufficient time to allowassociations between the electrode and the enzyme, such as Van der Waalsassociations, to mature. Attentively, a first binding moiety, such asbiotin or its binding complement avidin/streptavidin, can be attached tothe electrode and the enzyme bound to the first binding moiety throughan attached molecule of the binding complement.

The redox enzyme can comprise any number of enzymes that use an electroncarrier as a substrate, irrespective of whether the primary biologicallyrelevant direction of reaction is for the consumption or production ofsuch reduced electron carrier, since such reactions can be conducted inthe reverse direction. Examples of redox enzymes further include,without limitation, glucose oxidase (using NADH, available from severalsources, including number of types of this enzyme available from SigmaChemical), glucose-6-phosphate dehydrogenase (NADPH, BoehringerMannheim, Indianapolis, Ind.), 6-phosphogluconate dehydrogenase (NADPH,Boehringer Mannheim), malate dehydrogenase (NADH, Boehringer Mannheim),glyceraldehyde-3-phosphate dehydrogenase (NADH, Sigma, BoehringerMannheim), isocitrate dehydrogenase (NADH, Boehringer Mannheim; NADPH,Sigma), and .alpha.-ketoglutarate dehydrogenase complex (NADH, Sigma).

The redox enzyme can also be a transmembrane pump, such as a protonpump, that operates using an electron carrier as the energy source. Inthis case, enzyme can be associated with the electrode in the presenceof detergent and/or lipid carrier molecules which stabilize the activeconformation of the enzyme. As in other embodiments, an electrontransfer mediator can be used to increase the efficiency of electrontransfer to the electrode.

Associated electron carriers are readily available from commercialsuppliers such as Sigma and Boehringer Mannheim. The concentrations withthe reduced form of such electron carriers can be as high as possiblewithout disrupting the function of the redox enzyme. The salt and bufferconditions are designed based on, as a starting point, the ampleavailable knowledge of appropriate conditions for the redox enzyme. Suchenzyme conditions are typically available, for example, from suppliersof such enzymes.

In another embodiment where the fuel cells 30 need to be physicallyreplaced while the AC equipment is running, the inverter 40 receives aback-up energy source such as a small battery or a high capacitycapacitor. A current sensor is provided to sense current from thebattery unit 30. Once the current is interrupted during operationindicating that the energy storage units are being replaced or that ithas lost power, the inverter is connected to the back up energy sourceby a solid state switch or a relay. In this manner, the user-replaceablebattery units 30 can be substituted in the field without interruptingpower to the appliance by using the back-up energy source. The inverter40 receives a low DC voltage input in electrical communication andprovides a source of high DC voltage. The AC voltage to an appliance maybe by an electrical lead directly from the voltage converter to theappliance or via a switch mechanism or an electrical plug or socket. Inone embodiment, a standard AC wall plug connected to the inverter 40operably supplies the high DC voltage to an appliance.

The back-up energy storage device can also be a conventional battery ora supercapacitor, which is a component intermediate between a capacitorand a battery in terms of energy and power. The supercapacitor can beany electrochemical system using at least the surface properties of anideally polarizable material of high specific surface area. In otherwords, the super-capacitor is an electrochemical capacitor of highcapacitance.

During charging of the supercapacitor, there is a build-up of ionicspecies on either side of the two electrodes, at the ideally polarizablematerial/electrolyte interface. There may also be oxidation-reductionreactions in the presence of redox sites, resulting in apseudocapacitive system. Supercapacitors based on the principle of thedouble layer have been manufactured from a variety of materials. Thesesupercapacitors are assembled from two carbon electrodes having a highspecific surface area. In general, the capacitors include current leads,a separator lying between the electrodes, an electrolyte and a packagesealed with respect to the environment. One component of asupercapacitor consists of the electrolyte which, typically, comprises asolution of a salt, that is to say a combination of a salt and asolvent. In general, the electrolytes are low-viscosity liquids and havea high conductivity over a wide temperature range. They must also be oflow cost, chemically and electrochemically stable and compatible withcarbon or the other materials of which the electrodes are composed.

One exemplary super-capacitor is disclosed in U.S. Pat. No. 6,671,166,the content of which is incorporated by reference. As discussed therein,a high power capacitor ideally polarizable has a positive electrode andits current collector, a negative electrode and its current collector,said electrodes comprising a carbon containing material with highspecific surface area, a separator and a non-aqueous liquid electrolyteimpregnating said separator and said electrodes. The non-aqueous liquidelectrolyte is an organic solution of a sodium or potassium oralkalin-earth metal salt, on their own or mixed in a solvent containingan acid.

The inverter 40 can be a step-up transformer capable of amplifying lowDC voltage to high DC voltage. The term “low voltage DC” generallyencompasses voltages within the range from about 5 volts to about 50volts DC and more preferably from about 6 volts to about 36 volts DC andeven more preferably from about 8 volts to about 24 volts DC.Particularly preferred low voltages are about 8, 12, 24 or 36 volts witha variation of about 4 volts. High voltage AC encompasses voltageswithin the range from about 280 to about 480 volts AC. At high voltagelevels power may be supplied over long distances with a voltage dropwith minimal adverse effect on the system. As a result, the user caneffectively power an end appliance at a great distance from the powersource and portable converter. This is advantageous in a situation wherea mobile appliance is energized by the system. The mobile power unit andthe appliance, singly or in combination, may be moved widely and freely.

In one embodiment, the inverter can be pulse-width modulated inverter. APWM inverter is controlled by a control circuit, and the output of thePWM inverter is supplied to a sine wave filter (LC low-pass filter). Thesine filter includes an LC filter composed of a reactor and a capacitor,and a damping circuit which is a serial circuit of a resistor and acapacitor. The damping circuit is connected in parallel with thecapacitor in order to limit oscillation waveforms accompanying theresonance of the reactor and the capacitor. The control circuitcomprises a mean value circuit, an automatic voltage regulator (AVR), aninstantaneous voltage command value generator, and a PWM signalgenerator. First, a voltage detector is connected to the output of thesine filter to detect the instantaneous output voltage V of the sinefilter. The output voltage V is inputted to the mean value circuit. Themean value circuit produces the mean value of the instantaneous outputvoltage. The mean value is subtracted from a predetermined voltagereference value by a summing point, and the difference is supplied tothe automatic voltage regulator. The automatic voltage regulatorcorrects the voltage reference value so that the difference becomeszero, and supplies the resultant corrected voltage reference value tothe instantaneous voltage command value generator. The instantaneousvoltage command value generator, receiving the corrected voltagereference value VA and a predetermined frequency reference value,generates a sinusoidal instantaneous voltage command value havingamplitude determined by the corrected voltage reference value VA and afrequency determined by the frequency reference value. The outputvoltage V is subtracted from the instantaneous voltage command value bya summing point 82, and the difference is provided to a gain adjuster.The output of the gain adjuster is added to the voltage command value bya summing point that outputs a corrected voltage command value to thePWM signal generator. The PWM signal generator outputs a pulse signalcorresponding to the corrected voltage command value and controls thePWM inverter by the pulse signal. The foregoing describes the control ofone PWM inverter in one embodiment. In another embodiment, a pluralityof PWM inverters can be connected in parallel to supply power to acommon load.

In one embodiment, the fuel cell 30 has a microcontroller embeddedtherein. The microcontroller provides the appliance with variousinformation items such as fuel cell conditions, fuel cell chargecapacity, and a manufacturing company of the fuel cell. Typically,communications between the fuel cell microcontroller and the applianceare done over a serial RS-232 protocol. Other protocols includeUniversal Serial Bus (USB), SCSI, or Firewire. In this manner, the smartfuel cell can provide information about its residual capacity to theappliance so as to display a fuel cell state relevant to the residualcapacity of the fuel cell.

As described above, while the smart fuel cell has a function of offeringthe information on the residual amount of fuel cell capacity, and it isrequired to exactly estimate the fuel cell capacity changeable inaccordance with various environmental elements in order to offer exactfuel cell residual capacity information. Thus, the smart fuel cell setsup a new reference capacity in accordance with the changes of fuel cellcapacity, and provides present residual capacity information based onthe reference capacity. For the purpose of establishing the newreference capacity, the smart fuel cell carries out calibration when anoutput voltage becomes lower than a predetermined level. The calibrationis used for re-establishing the reference capacity of the fuel cell witha measured value of a total charge capacity of a fuel cell. During thecalibration, a discharge starts from a full-charged state, and theamount discharged until the output voltage of the smart fuel cellbecomes lower than the predetermined voltage level is established as areference capacity. In case that the fuel cell continues to bedischarged after the calibration, the reference capacity is set byperforming a re-calibration after the former discharge is finished.

In one embodiment where the appliance is a computer, a power managementsoftware detects a state of low fuel cell (LB) in which the fuel cellresidual capacity is reduced less than 10%, and displays a warning for auser. Then, if the smart fuel cell continues to discharge, and thus alow low fuel cell voltage is detected, i.e. if the fuel cell residualcapacity is reduced less than a predetermined amount, e.g., less than3%, the power management system stores data by making an operatingsystem (OS) program to protect current data at work. This case is calleda low low fuel cell (LLB) state. The OS program serves to support apower management function such as advanced power manager (APM) oradvanced configuration and power interface (ACPI), and for instance, aWINDOWS type of OS (operating system) of the MICROSOFT Corporationbelongs to the program. The OS program allows the data being processedof the present system to be stored in a hard disk drive, and after theoperation, the power management system finishes the system by blockingthe power source provided from the smart fuel cell. It is understoodthat the examples and embodiments described herein are for illustrativepurposes only and that various modifications or changes in light thereofwill be suggested to persons skilled in the art and are to be includedwithin the spirit and purview of this application and scope of theappended claims. All publications, patents, and patent applicationscited herein are hereby incorporated by reference in their entirety.

What is claimed is:
 1. A memory device, comprising: an upper conductivelayer, a lower conductive layer, and a memory resistive (memristive)matrix positioned between the upper and lower conductive layers to forma low-resistance conduction path for one condition and a high-resistanceconduction path for another condition and wherein at least oneconductive layer comprises a bimetallic electrode.
 2. The memory deviceof claim 1, comprising a second array of memory structures disposed inrows and columns and constructed either above or below the memristivematrix.
 3. The memory device of claim 1, further comprising a drivercircuit for selectively controlling first signal electrodes or secondsignal electrodes.
 4. The memory device of claim 3, wherein the circuitincludes one or more of a sense amplifier, an input-output buffer, an Xaddress decoder, a Y address decoder, and an address buffer.
 5. Thememory device of claim 1, wherein the substrate includes asilicon-on-insulator wafer.
 6. The memory device of claim 1, wherein thememory resistive layer is spin-coated over the substrate.
 7. The memorydevice of claim 1, wherein the resistive layer form memory circuits,analog circuits, hybrid circuits, or logic circuits.
 8. The memorydevice of claim 1, wherein the resistive layer forms one or more fuzzylogic circuits.
 9. The memory device of claim 1, wherein the memorydevice comprises a solid state storage device.
 10. The memory device ofclaim 1, further comprising an array of redundant memory elements. 11.The memory device of claim 10, wherein the redundant array is a row or acolumn of redundant resistive-elements.
 12. The memory device of claim1, further comprising memory devices forming a plurality of memoryhierarchy to optimize data access speed.
 13. A memory device,comprising: an upper conductive layer, a lower conductive layer, and aresistive matrix positioned between the upper and lower conductivelayers, wherein the resistive matrix forms a low-resistance conductionpath for one condition and a high-resistance conduction path for anothercondition and wherein at least one conductive layer comprises abimetallic electrode.
 14. A memory electronic device, comprising: asubstrate; a first layer fabricated in silicon using semiconductorfabrication techniques; a lower conductive layer formed above the firstlayer; a second layer formed above the lower conductive layer, thesecond layer having a matrix of resistive memory elements; and an upperconductive layer formed above the matrix, wherein at least one of thelower and upper conductive layers is bimetallic with a conductingportion and a metallic portion.
 15. The device of claim 14, comprising athird layer formed above the second layer, the third layer having one ormore resistive-bonding areas and one or more resistive memory elementsbonded to the third layer resistive bonding areas.
 16. The device ofclaim 14, wherein the resistive-elements are spin-coated on the secondlayer.
 17. The device of claim 14, wherein the resistive layer comprisesa combination of two resistive elements that in combination have a zerotemperature coefficient.
 18. The device of claim 14, comprising aplurality of resistive memory elements with zero temperaturecoefficient.
 19. The device of claim 18, comprising a first resistiveelement with a positive temperature coefficient and the second resistiveelement with a negative temperature coefficient.
 20. The device of claim18, wherein the temperature coefficient is selected such that a seriesor parallel combination of two elements results in a resistive elementhaving zero temperature coefficient.